Esempio n. 1
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def _bql_logpdf(bdb, population_id, generator_id, modelnos, targets,
                constraints):
    # P(T | C) = \sum_M P(T, M | C)
    # = \sum_M P(T | C, M) P(M | C)
    # = \sum_M P(T | C, M) P(M) P(C | M) / P(C)
    # = \sum_M P(T | C, M) P(M) P(C | M) / \sum_M' P(C, M')
    # = \sum_M P(T | C, M) P(M) P(C | M) / \sum_M' P(C | M') P(M')
    #
    # For a generator M, logpdf(M) computes P(T | C, M), and
    # loglikelihood(M) computes P(C | M).  For now, we weigh each
    # generator uniformly; eventually, we ought to allow the user to
    # specify a prior weight (XXX and update some kind of posterior
    # weight?).
    rowid, constraints = _retrieve_rowid_constraints(bdb, population_id,
                                                     constraints)

    def logpdf(generator_id, backend):
        return backend.logpdf_joint(bdb, generator_id, modelnos, rowid,
                                    targets, constraints)

    def loglikelihood(generator_id, backend):
        if not constraints:
            return 0
        return backend.logpdf_joint(bdb, generator_id, modelnos, rowid,
                                    constraints, [])

    generator_ids = _retrieve_generator_ids(bdb, population_id, generator_id)
    backends = [core.bayesdb_generator_backend(bdb, g) for g in generator_ids]
    loglikelihoods = map(loglikelihood, generator_ids, backends)
    logpdfs = map(logpdf, generator_ids, backends)
    return logavgexp_weighted(loglikelihoods, logpdfs)
Esempio n. 2
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def _bql_logpdf(bdb, population_id, generator_id, modelnos, targets,
        constraints):
    # P(T | C) = \sum_M P(T, M | C)
    # = \sum_M P(T | C, M) P(M | C)
    # = \sum_M P(T | C, M) P(M) P(C | M) / P(C)
    # = \sum_M P(T | C, M) P(M) P(C | M) / \sum_M' P(C, M')
    # = \sum_M P(T | C, M) P(M) P(C | M) / \sum_M' P(C | M') P(M')
    #
    # For a generator M, logpdf(M) computes P(T | C, M), and
    # loglikelihood(M) computes P(C | M).  For now, we weigh each
    # generator uniformly; eventually, we ought to allow the user to
    # specify a prior weight (XXX and update some kind of posterior
    # weight?).
    rowid, constraints = _retrieve_rowid_constraints(
        bdb, population_id, constraints)
    def logpdf(generator_id, backend):
        return backend.logpdf_joint(
            bdb, generator_id, modelnos, rowid, targets, constraints)
    def loglikelihood(generator_id, backend):
        if not constraints:
            return 0
        return backend.logpdf_joint(
            bdb, generator_id, modelnos, rowid, constraints, [])
    generator_ids = _retrieve_generator_ids(bdb, population_id, generator_id)
    backends = [
        core.bayesdb_generator_backend(bdb, g)
        for g in generator_ids
    ]
    loglikelihoods = map(loglikelihood, generator_ids, backends)
    logpdfs = map(logpdf, generator_ids, backends)
    return logavgexp_weighted(loglikelihoods, logpdfs)
Esempio n. 3
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 def generator_mutinf(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     return backend.column_mutual_information(bdb,
                                              generator_id,
                                              modelnos,
                                              colnos0,
                                              colnos1,
                                              constraints=constraints,
                                              numsamples=numsamples)
Esempio n. 4
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def bayesdb_simulate(
        bdb, population_id, generator_id, modelnos, constraints, colnos,
        numpredictions=1, accuracy=None):
    """Simulate rows from a generative model, subject to constraints.

    Returns a list of `numpredictions` tuples, with a value for each
    column specified in the list `colnos`, conditioned on the
    constraints in the list `constraints` of tuples ``(colno,
    value)``.

    The results are simulated from the predictive distribution on
    fresh rows.
    """
    modelnos = _retrieve_modelnos(modelnos)
    rowid, constraints = _retrieve_rowid_constraints(
        bdb, population_id, constraints)
    def loglikelihood(generator_id, backend):
        if not constraints:
            return 0
        return backend.logpdf_joint(
            bdb, generator_id, modelnos, rowid, constraints, [])
    def simulate(generator_id, backend, n):
        return backend.simulate_joint(
            bdb, generator_id, modelnos, rowid, colnos, constraints,
            num_samples=n, accuracy=accuracy)
    generator_ids = _retrieve_generator_ids(bdb, population_id, generator_id)
    backends = [
        core.bayesdb_generator_backend(bdb, generator_id)
        for generator_id in generator_ids
    ]
    if len(generator_ids) > 1:
        loglikelihoods = map(loglikelihood, generator_ids, backends)
        likelihoods = map(math.exp, loglikelihoods)
        total_likelihood = sum(likelihoods)
        if total_likelihood == 0:
            # XXX Show the constraints with symbolic names.
            raise BQLError(bdb, 'Impossible constraints: %r' % (constraints,))
        probabilities = [
            likelihood / total_likelihood
            for likelihood in likelihoods
        ]
        countses = bdb.np_prng.multinomial(
            numpredictions, probabilities, size=1)
        counts = countses[0]
    elif len(generator_ids) == 1:
        counts = [numpredictions]
    else:
        counts = []
    rowses = map(simulate, generator_ids, backends, counts)
    all_rows = [row for rows in rowses for row in rows]
    assert all(isinstance(row, (tuple, list)) for row in all_rows)
    return all_rows
Esempio n. 5
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def bql_predict(
        bdb, population_id, generator_id, modelnos, rowid, colno, threshold,
        numsamples):
    # XXX Randomly sample 1 generator from the population, until we figure out
    # how to aggregate imputations across different hypotheses.
    modelnos = _retrieve_modelnos(modelnos)
    if generator_id is None:
        generator_ids = core.bayesdb_population_generators(bdb, population_id)
        index = bdb.np_prng.randint(0, high=len(generator_ids))
        generator_id = generator_ids[index]
    backend = core.bayesdb_generator_backend(bdb, generator_id)
    return backend.predict(
        bdb, generator_id, modelnos, rowid, colno, threshold,
        numsamples=numsamples)
Esempio n. 6
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def bql_predict_confidence(
        bdb, population_id, generator_id, modelnos, rowid, colno, numsamples):
    # XXX Do real imputation here!
    # XXX Randomly sample 1 generator from the population, until we figure out
    # how to aggregate imputations across different hypotheses.
    if generator_id is None:
        generator_ids = core.bayesdb_population_generators(bdb, population_id)
        index = bdb.np_prng.randint(0, high=len(generator_ids))
        generator_id = generator_ids[index]
    modelnos = _retrieve_modelnos(modelnos)
    backend = core.bayesdb_generator_backend(bdb, generator_id)
    value, confidence = backend.predict_confidence(
        bdb, generator_id, modelnos, rowid, colno, numsamples=numsamples)
    # XXX Whattakludge!
    return json.dumps({'value': value, 'confidence': confidence})
Esempio n. 7
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def bql_predict(bdb, population_id, generator_id, modelnos, rowid, colno,
                threshold, numsamples):
    # XXX Randomly sample 1 generator from the population, until we figure out
    # how to aggregate imputations across different hypotheses.
    modelnos = _retrieve_modelnos(modelnos)
    if generator_id is None:
        generator_ids = core.bayesdb_population_generators(bdb, population_id)
        index = bdb.np_prng.randint(0, high=len(generator_ids))
        generator_id = generator_ids[index]
    backend = core.bayesdb_generator_backend(bdb, generator_id)
    return backend.predict(bdb,
                           generator_id,
                           modelnos,
                           rowid,
                           colno,
                           threshold,
                           numsamples=numsamples)
Esempio n. 8
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def bql_predict_confidence(bdb, population_id, generator_id, modelnos, rowid,
                           colno, numsamples):
    # XXX Do real imputation here!
    # XXX Randomly sample 1 generator from the population, until we figure out
    # how to aggregate imputations across different hypotheses.
    if generator_id is None:
        generator_ids = core.bayesdb_population_generators(bdb, population_id)
        index = bdb.np_prng.randint(0, high=len(generator_ids))
        generator_id = generator_ids[index]
    modelnos = _retrieve_modelnos(modelnos)
    backend = core.bayesdb_generator_backend(bdb, generator_id)
    value, confidence = backend.predict_confidence(bdb,
                                                   generator_id,
                                                   modelnos,
                                                   rowid,
                                                   colno,
                                                   numsamples=numsamples)
    # XXX Whattakludge!
    return json.dumps({'value': value, 'confidence': confidence})
Esempio n. 9
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 def dump_models(self, line, cell=None):
     population_name = line
     if not bayesdb_has_population(self._bdb, population_name):
         raise ValueError('No such population: %r' % (population_name, ))
     population_id = bayesdb_get_population(self._bdb, population_name)
     generators = bayesdb_population_generators(self._bdb, population_id)
     if len(generators) == 0:
         raise ValueError('No generator for population %r' %
                          (population_name, ))
     if len(generators) > 1:
         raise ValueError('Generator not unique for population %r' %
                          (population_name, ))
     generator_id = generators[0]
     backend = bayesdb_generator_backend(self._bdb, generator_id)
     if backend.name() != 'cgpm':
         self.write_stderr('%dump_models requires generator from the '
                           'cgpm backend')
         return
     j = backend.json_ready_models(self._bdb, population_id, generator_id)
     path = population_name + '_models.json'
     with open(path, 'w') as outfile:
         json.dump(j, outfile, indent=2)
Esempio n. 10
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 def generator_predprob(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     return backend.logpdf_joint(
         bdb, generator_id, modelnos, fresh_rowid, cgpm_targets,
         cgpm_constraints)
Esempio n. 11
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 def generator_similarity(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     return backend.predictive_relevance(
         bdb, generator_id, modelnos, rowid_target, rowid_query,
         hypotheticals, colno)
Esempio n. 12
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 def generator_similarity(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     # XXX Change [colno] to colno by updating BayesDB_Backend.
     similarity_list = backend.row_similarity(
         bdb, generator_id, modelnos, rowid, target_rowid, [colno])
     return stats.arithmetic_mean(similarity_list)
Esempio n. 13
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def bayesdb_simulate(bdb,
                     population_id,
                     generator_id,
                     modelnos,
                     constraints,
                     colnos,
                     numpredictions=1,
                     accuracy=None):
    """Simulate rows from a generative model, subject to constraints.

    Returns a list of `numpredictions` tuples, with a value for each
    column specified in the list `colnos`, conditioned on the
    constraints in the list `constraints` of tuples ``(colno,
    value)``.

    The results are simulated from the predictive distribution on
    fresh rows.
    """
    modelnos = _retrieve_modelnos(modelnos)
    rowid, constraints = _retrieve_rowid_constraints(bdb, population_id,
                                                     constraints)

    def loglikelihood(generator_id, backend):
        if not constraints:
            return 0
        return backend.logpdf_joint(bdb, generator_id, modelnos, rowid,
                                    constraints, [])

    def simulate(generator_id, backend, n):
        return backend.simulate_joint(bdb,
                                      generator_id,
                                      modelnos,
                                      rowid,
                                      colnos,
                                      constraints,
                                      num_samples=n,
                                      accuracy=accuracy)

    generator_ids = _retrieve_generator_ids(bdb, population_id, generator_id)
    backends = [
        core.bayesdb_generator_backend(bdb, generator_id)
        for generator_id in generator_ids
    ]
    if len(generator_ids) > 1:
        loglikelihoods = map(loglikelihood, generator_ids, backends)
        likelihoods = map(math.exp, loglikelihoods)
        total_likelihood = sum(likelihoods)
        if total_likelihood == 0:
            # XXX Show the constraints with symbolic names.
            raise BQLError(bdb, 'Impossible constraints: %r' % (constraints, ))
        probabilities = [
            likelihood / total_likelihood for likelihood in likelihoods
        ]
        countses = bdb.np_prng.multinomial(numpredictions,
                                           probabilities,
                                           size=1)
        counts = countses[0]
    elif len(generator_ids) == 1:
        counts = [numpredictions]
    else:
        counts = []
    rowses = map(simulate, generator_ids, backends, counts)
    all_rows = [row for rows in rowses for row in rows]
    assert all(isinstance(row, (tuple, list)) for row in all_rows)
    return all_rows
Esempio n. 14
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 def generator_predprob(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     return backend.logpdf_joint(bdb, generator_id, modelnos, fresh_rowid,
                                 cgpm_targets, cgpm_constraints)
Esempio n. 15
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 def generator_similarity(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     return backend.predictive_relevance(bdb, generator_id, modelnos,
                                         rowid_target, rowid_query,
                                         hypotheticals, colno)
Esempio n. 16
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 def generator_similarity(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     # XXX Change [colno] to colno by updating BayesDB_Backend.
     similarity_list = backend.row_similarity(bdb, generator_id, modelnos,
                                              rowid, target_rowid, [colno])
     return stats.arithmetic_mean(similarity_list)
Esempio n. 17
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def execute_phrase(bdb, phrase, bindings=()):
    """Execute the BQL AST phrase `phrase` and return a cursor of results."""
    if isinstance(phrase, ast.Parametrized):
        n_numpar = phrase.n_numpar
        nampar_map = phrase.nampar_map
        phrase = phrase.phrase
        assert 0 < n_numpar
    else:
        n_numpar = 0
        nampar_map = None
        # Ignore extraneous bindings.  XXX Bad idea?

    if ast.is_query(phrase):
        # Compile the query in the transaction in case we need to
        # execute subqueries to determine column lists.  Compiling is
        # a quick tree descent, so this should be fast.
        out = compiler.Output(n_numpar, nampar_map, bindings)
        with bdb.savepoint():
            compiler.compile_query(bdb, phrase, out)
        winders, unwinders = out.getwindings()
        return execute_wound(bdb, winders, unwinders, out.getvalue(),
                             out.getbindings())

    if isinstance(phrase, ast.Begin):
        txn.bayesdb_begin_transaction(bdb)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.Rollback):
        txn.bayesdb_rollback_transaction(bdb)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.Commit):
        txn.bayesdb_commit_transaction(bdb)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.CreateTabAs):
        assert ast.is_query(phrase.query)
        with bdb.savepoint():
            if core.bayesdb_has_table(bdb, phrase.name):
                if phrase.ifnotexists:
                    return empty_cursor(bdb)
                else:
                    raise BQLError(
                        bdb, 'Name already defined as table: %s' %
                        (repr(phrase.name), ))
            out = compiler.Output(n_numpar, nampar_map, bindings)
            qt = sqlite3_quote_name(phrase.name)
            temp = 'TEMP ' if phrase.temp else ''
            ifnotexists = 'IF NOT EXISTS ' if phrase.ifnotexists else ''
            out.write('CREATE %sTABLE %s%s AS ' % (temp, ifnotexists, qt))
            compiler.compile_query(bdb, phrase.query, out)
            winders, unwinders = out.getwindings()
            with compiler.bayesdb_wind(bdb, winders, unwinders):
                bdb.sql_execute(out.getvalue(), out.getbindings())
        return empty_cursor(bdb)

    if isinstance(phrase, ast.CreateTabCsv):
        with bdb.savepoint():
            table_exists = core.bayesdb_has_table(bdb, phrase.name)
            if table_exists:
                if phrase.ifnotexists:
                    return empty_cursor(bdb)
                else:
                    raise BQLError(
                        bdb,
                        'Table already exists: %s' % (repr(phrase.name), ))
            bayesdb_read_csv_file(bdb,
                                  phrase.name,
                                  phrase.csv,
                                  header=True,
                                  create=True)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropTab):
        with bdb.savepoint():
            sql = 'SELECT COUNT(*) FROM bayesdb_population WHERE tabname = ?'
            cursor = bdb.sql_execute(sql, (phrase.name, ))
            if 0 < cursor_value(cursor):
                raise BQLError(
                    bdb, 'Table still in use by populations: %s' %
                    (repr(phrase.name), ))
            bdb.sql_execute('DELETE FROM bayesdb_column WHERE tabname = ?',
                            (phrase.name, ))
            ifexists = 'IF EXISTS ' if phrase.ifexists else ''
            qt = sqlite3_quote_name(phrase.name)
            return bdb.sql_execute('DROP TABLE %s%s' % (ifexists, qt))

    if isinstance(phrase, ast.AlterTab):
        with bdb.savepoint():
            table = phrase.table
            if not core.bayesdb_has_table(bdb, table):
                raise BQLError(bdb, 'No such table: %s' % (repr(table), ))
            for cmd in phrase.commands:
                if isinstance(cmd, ast.AlterTabRenameTab):
                    # If the names differ only in case, we have to do
                    # some extra work because SQLite will reject the
                    # table rename.  Note that we may even have table
                    # == cmd.name here, but if the stored table name
                    # differs in case from cmd.name, we want to update
                    # it anyway.
                    if casefold(table) == casefold(cmd.name):
                        # Go via a temporary table.
                        temp = table + '_temp'
                        while core.bayesdb_has_table(bdb, temp):
                            temp += '_temp'
                        rename_table(bdb, table, temp)
                        rename_table(bdb, temp, cmd.name)
                    else:
                        # Make sure nothing else has this name and
                        # rename it.
                        if core.bayesdb_has_table(bdb, cmd.name):
                            raise BQLError(
                                bdb, 'Name already defined as table: %s' %
                                (repr(cmd.name), ))
                        rename_table(bdb, table, cmd.name)
                    # If table has implicit population, rename it too.
                    if core.bayesdb_table_has_implicit_population(
                            bdb, cmd.name):
                        populations = \
                            core.bayesdb_table_populations(bdb, cmd.name)
                        assert len(populations) == 1
                        population_name = core.bayesdb_population_name(
                            bdb, populations[0])
                        qt = sqlite3_quote_name(cmd.name)
                        qp = sqlite3_quote_name(population_name)
                        bdb.execute('ALTER POPULATION %s RENAME TO %s' %
                                    (qp, qt))
                    # Remember the new name for subsequent commands.
                    table = cmd.name
                elif isinstance(cmd, ast.AlterTabRenameCol):
                    # XXX Need to deal with this in the compiler.
                    raise NotImplementedError('Renaming columns'
                                              ' not yet implemented.')
                    # Make sure the old name exist and the new name does not.
                    old_folded = casefold(cmd.old)
                    new_folded = casefold(cmd.new)
                    if old_folded != new_folded:
                        if not core.bayesdb_table_has_column(
                                bdb, table, cmd.old):
                            raise BQLError(
                                bdb, 'No such column in table %s'
                                ': %s' % (repr(table), repr(cmd.old)))
                        if core.bayesdb_table_has_column(bdb, table, cmd.new):
                            raise BQLError(
                                bdb, 'Column already exists'
                                ' in table %s: %s' %
                                (repr(table), repr(cmd.new)))
                    # Update bayesdb_column.  Everything else refers
                    # to columns by (tabname, colno) pairs rather than
                    # by names.
                    update_column_sql = '''
                        UPDATE bayesdb_column SET name = :new
                            WHERE tabname = :table AND name = :old
                    '''
                    total_changes = bdb._sqlite3.totalchanges()
                    bdb.sql_execute(update_column_sql, {
                        'table': table,
                        'old': cmd.old,
                        'new': cmd.new,
                    })
                    assert bdb._sqlite3.totalchanges() - total_changes == 1
                    # ...except backends may have the (case-folded) name cached.
                    if old_folded != new_folded:
                        populations_sql = '''
                            SELECT id FROM bayesdb_population WHERE tabname = ?
                        '''
                        cursor = bdb.sql_execute(populations_sql, (table, ))
                        generators = [
                            core.bayesdb_population_generators(
                                bdb, population_id)
                            for (population_id, ) in cursor
                        ]
                        for generator_id in set(generators):
                            backend = core.bayesdb_generator_backend(
                                bdb, generator_id)
                            backend.rename_column(bdb, generator_id,
                                                  old_folded, new_folded)
                else:
                    assert False, 'Invalid alter table command: %s' % \
                        (cmd,)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.GuessSchema):
        if not core.bayesdb_has_table(bdb, phrase.table):
            raise BQLError(bdb, 'No such table : %s' % phrase.table)
        out = compiler.Output(0, {}, {})
        with bdb.savepoint():
            qt = sqlite3_quote_name(phrase.table)
            temptable = bdb.temp_table_name()
            qtt = sqlite3_quote_name(temptable)
            cursor = bdb.sql_execute('SELECT * FROM %s' % (qt, ))
            column_names = [d[0] for d in cursor.description]
            rows = cursor.fetchall()
            stattypes = bayesdb_guess_stattypes(column_names, rows)
            distinct_value_counts = [
                len(set([row[i] for row in rows]))
                for i in range(len(column_names))
            ]
            out.winder(
                '''
                CREATE TEMP TABLE %s (
                    column TEXT,
                    stattype TEXT,
                    num_distinct INTEGER,
                    reason TEXT
                )
            ''' % (qtt, ), ())
            for cn, st, ct in zip(column_names, stattypes,
                                  distinct_value_counts):
                out.winder(
                    '''
                    INSERT INTO %s VALUES (?, ?, ?, ?)
                ''' % (qtt), (cn, st[0], ct, st[1]))
            out.write('SELECT * FROM %s' % (qtt, ))
            out.unwinder('DROP TABLE %s' % (qtt, ), ())
        winders, unwinders = out.getwindings()
        return execute_wound(bdb, winders, unwinders, out.getvalue(),
                             out.getbindings())

    if isinstance(phrase, ast.CreatePop):
        with bdb.savepoint():
            _create_population(bdb, phrase)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropPop):
        with bdb.savepoint():
            if not core.bayesdb_has_population(bdb, phrase.name):
                if phrase.ifexists:
                    return empty_cursor(bdb)
                raise BQLError(bdb, 'No such population: %r' % (phrase.name, ))
            population_id = core.bayesdb_get_population(bdb, phrase.name)
            generator_ids = core.bayesdb_population_generators(
                bdb, population_id)
            if generator_ids:
                generators = [
                    core.bayesdb_generator_name(bdb, gid)
                    for gid in generator_ids
                ]
                raise BQLError(
                    bdb, 'Population %r still has generators: %r' %
                    (phrase.name, generators))
            # XXX helpful error checking if generators still exist
            # XXX check change counts
            bdb.sql_execute(
                '''
                DELETE FROM bayesdb_variable WHERE population_id = ?
            ''', (population_id, ))
            bdb.sql_execute(
                '''
                DELETE FROM bayesdb_population WHERE id = ?
            ''', (population_id, ))
        return empty_cursor(bdb)

    if isinstance(phrase, ast.AlterPop):
        with bdb.savepoint():
            population = phrase.population
            if not core.bayesdb_has_population(bdb, population):
                raise BQLError(bdb,
                               'No such population: %s' % (repr(population), ))
            population_id = core.bayesdb_get_population(bdb, population)
            for cmd in phrase.commands:
                if isinstance(cmd, ast.AlterPopRenamePop):
                    table = core.bayesdb_population_table(bdb, population_id)
                    # Prevent renaming of implicit population directly, unless
                    # being called by ast.AlterTabRenameTab in which case the
                    # table name and population name will not be matching.
                    if core.bayesdb_population_is_implicit(bdb, population_id) \
                            and casefold(population) == casefold(table):
                        raise BQLError(
                            bdb, 'Cannot rename implicit'
                            'population %s; rename base table instead' %
                            (population, ))
                    # Make sure nothing else has this name.
                    if casefold(population) != casefold(cmd.name):
                        if core.bayesdb_has_population(bdb, cmd.name):
                            raise BQLError(
                                bdb, 'Name already defined as population'
                                ': %s' % (repr(cmd.name), ))
                    # Update bayesdb_population.  Everything else
                    # refers to it by id.
                    update_generator_sql = '''
                        UPDATE bayesdb_population SET name = ? WHERE id = ?
                    '''
                    total_changes = bdb._sqlite3.totalchanges()
                    bdb.sql_execute(update_generator_sql,
                                    (cmd.name, population_id))
                    assert bdb._sqlite3.totalchanges() - total_changes == 1
                    # If population has implicit generator, rename it too.
                    if core.bayesdb_population_has_implicit_generator(
                            bdb, population_id):
                        generators = core.bayesdb_population_generators(
                            bdb, population_id)
                        assert len(generators) == 1
                        generator_name = core.bayesdb_generator_name(
                            bdb, generators[0])
                        qp = sqlite3_quote_name(cmd.name)
                        qg = sqlite3_quote_name(generator_name)
                        bdb.execute('ALTER GENERATOR %s RENAME TO %s' % (
                            qg,
                            qp,
                        ))
                    # Remember the new name for subsequent commands.
                    population = cmd.name
                elif isinstance(cmd, ast.AlterPopAddVar):
                    # Ensure column exists in base table.
                    table = core.bayesdb_population_table(bdb, population_id)
                    if not core.bayesdb_table_has_column(bdb, table, cmd.name):
                        raise BQLError(
                            bdb,
                            'No such variable in base table: %s' % (cmd.name))
                    # Ensure variable not already in population.
                    if core.bayesdb_has_variable(bdb, population_id, None,
                                                 cmd.name):
                        raise BQLError(
                            bdb,
                            'Variable already in population: %s' % (cmd.name))
                    # Ensure there is at least observation in the column.
                    qt = sqlite3_quote_name(table)
                    qc = sqlite3_quote_name(cmd.name)
                    cursor = bdb.sql_execute(
                        'SELECT COUNT(*) FROM %s WHERE %s IS NOT NULL' %
                        (qt, qc))
                    if cursor_value(cursor) == 0:
                        raise BQLError(
                            bdb, 'Cannot add variable without any values: %s' %
                            (cmd.name))
                    # If stattype is None, guess.
                    if cmd.stattype is None:
                        cursor = bdb.sql_execute('SELECT %s FROM %s' %
                                                 (qc, qt))
                        rows = cursor.fetchall()
                        [stattype,
                         reason] = bayesdb_guess_stattypes([cmd.name], rows)[0]
                        # Fail if trying to model a key.
                        if stattype == 'key':
                            raise BQLError(
                                bdb, 'Values in column %s appear to be keys.' %
                                (cmd.name, ))
                        # Fail if cannot determine a stattype.
                        elif stattype == 'ignore':
                            raise BQLError(
                                bdb, 'Failed to determine a stattype for %s, '
                                'please specify one manually.' % (cmd.name, ))
                    # If user specified stattype, ensure it exists.
                    elif not core.bayesdb_has_stattype(bdb, cmd.stattype):
                        raise BQLError(bdb,
                                       'Invalid stattype: %s' % (cmd.stattype))
                    else:
                        stattype = cmd.stattype
                    # Check that strings are not being modeled as numerical.
                    if stattype == 'numerical' \
                            and _column_contains_string(bdb, table, cmd.name):
                        raise BQLError(
                            bdb,
                            'Numerical column contains string values: %r ' %
                            (qc, ))
                    with bdb.savepoint():
                        # Add the variable to the population.
                        core.bayesdb_add_variable(bdb, population_id, cmd.name,
                                                  stattype)
                        colno = core.bayesdb_variable_number(
                            bdb, population_id, None, cmd.name)
                        # Add the variable to each (initialized) generator in
                        # the population.
                        generator_ids = filter(
                            lambda g: core.bayesdb_generator_modelnos(bdb, g),
                            core.bayesdb_population_generators(
                                bdb, population_id),
                        )
                        for generator_id in generator_ids:
                            backend = core.bayesdb_generator_backend(
                                bdb, generator_id)
                            backend.add_column(bdb, generator_id, colno)
                elif isinstance(cmd, ast.AlterPopStatType):
                    # Check the no generators are defined for this population.
                    generators = core.bayesdb_population_generators(
                        bdb, population_id)
                    if generators:
                        raise BQLError(
                            bdb,
                            'Cannot update statistical types for population '
                            '%s, it has generators: %s' % (
                                repr(population),
                                repr(generators),
                            ))
                    # Check all the variables are in the population.
                    unknown = [
                        c for c in cmd.names if not core.bayesdb_has_variable(
                            bdb, population_id, None, c)
                    ]
                    if unknown:
                        raise BQLError(
                            bdb, 'No such variables in population: %s' %
                            (repr(unknown)))
                    # Check the statistical type is valid.
                    if not core.bayesdb_has_stattype(bdb, cmd.stattype):
                        raise BQLError(
                            bdb, 'Invalid statistical type: %r' %
                            (repr(cmd.stattype), ))
                    # Check that strings are not being modeled as numerical.
                    if cmd.stattype == 'numerical':
                        table = core.bayesdb_population_table(
                            bdb, population_id)
                        numerical_string_vars = [
                            col for col in cmd.names
                            if _column_contains_string(bdb, table, col)
                        ]
                        if numerical_string_vars:
                            raise BQLError(
                                bdb, 'Columns with string values modeled as '
                                'numerical: %r' % (numerical_string_vars, ))
                    # Perform the stattype update.
                    colnos = [
                        core.bayesdb_variable_number(bdb, population_id, None,
                                                     c) for c in cmd.names
                    ]
                    qcolnos = ','.join('%d' % (colno, ) for colno in colnos)
                    update_stattype_sql = '''
                        UPDATE bayesdb_variable SET stattype = ?
                            WHERE population_id = ? AND colno IN (%s)
                    ''' % (qcolnos, )
                    bdb.sql_execute(update_stattype_sql, (
                        casefold(cmd.stattype),
                        population_id,
                    ))
                else:
                    assert False, 'Invalid ALTER POPULATION command: %s' % \
                        (repr(cmd),)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.CreateGen):
        # Find the population.
        if not core.bayesdb_has_population(bdb, phrase.population):
            raise BQLError(bdb,
                           'No such population: %r' % (phrase.population, ))
        population_id = core.bayesdb_get_population(bdb, phrase.population)

        # Find the backend, or use the default.
        backend_name = phrase.backend
        if phrase.backend is None:
            backend_name = 'cgpm'
        if backend_name not in bdb.backends:
            raise BQLError(bdb, 'No such backend: %s' % (repr(backend_name), ))
        backend = bdb.backends[backend_name]

        # Retrieve the (possibility implicit) generator name.
        generator_name = phrase.name or phrase.population
        implicit = 1 if phrase.name is None else 0

        with bdb.savepoint():
            if core.bayesdb_has_generator(bdb, population_id, generator_name):
                if not phrase.ifnotexists:
                    raise BQLError(
                        bdb, 'Name already defined as generator: %s' %
                        (repr(generator_name), ))
            else:
                # Insert a record into bayesdb_generator and get the
                # assigned id.
                bdb.sql_execute(
                    '''
                    INSERT INTO bayesdb_generator
                        (name, population_id, backend, implicit)
                        VALUES (?, ?, ?, ?)
                ''', (generator_name, population_id, backend.name(), implicit))
                generator_id = core.bayesdb_get_generator(
                    bdb, population_id, generator_name)
                # Do any backend-specific initialization.
                backend.create_generator(bdb, generator_id, phrase.schema)

        # All done.  Nothing to return.
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropGen):
        with bdb.savepoint():
            if not core.bayesdb_has_generator(bdb, None, phrase.name):
                if phrase.ifexists:
                    return empty_cursor(bdb)
                raise BQLError(bdb,
                               'No such generator: %s' % (repr(phrase.name), ))
            generator_id = core.bayesdb_get_generator(bdb, None, phrase.name)
            backend = core.bayesdb_generator_backend(bdb, generator_id)

            # Backend-specific destruction.
            backend.drop_generator(bdb, generator_id)

            # Drop latent variables, models, and, finally, generator.
            drop_columns_sql = '''
                DELETE FROM bayesdb_variable WHERE generator_id = ?
            '''
            bdb.sql_execute(drop_columns_sql, (generator_id, ))
            drop_model_sql = '''
                DELETE FROM bayesdb_generator_model WHERE generator_id = ?
            '''
            bdb.sql_execute(drop_model_sql, (generator_id, ))
            drop_generator_sql = '''
                DELETE FROM bayesdb_generator WHERE id = ?
            '''
            bdb.sql_execute(drop_generator_sql, (generator_id, ))
        return empty_cursor(bdb)

    if isinstance(phrase, ast.AlterGen):
        with bdb.savepoint():
            generator = phrase.generator
            if not core.bayesdb_has_generator(bdb, None, generator):
                raise BQLError(bdb,
                               'No such generator: %s' % (repr(generator), ))
            generator_id = core.bayesdb_get_generator(bdb, None, generator)
            cmds_generic = []
            for cmd in phrase.commands:
                if isinstance(cmd, ast.AlterGenRenameGen):
                    population_id = core.bayesdb_generator_population(
                        bdb, generator_id)
                    population = core.bayesdb_population_name(
                        bdb, population_id)
                    # Prevent renaming of implicit generator directly, unless
                    # being called by ast.AlterPopRenamePop in which case the
                    # population name and generator name will not be matching.
                    if core.bayesdb_population_is_implicit(bdb, generator_id) \
                            and casefold(generator) == casefold(population):
                        raise BQLError(
                            bdb, 'Cannot rename implicit '
                            'generator; rename base population instead')
                    # Disable modelnos with AlterGenRenameGen.
                    if phrase.modelnos is not None:
                        raise BQLError(bdb, 'Cannot specify models for RENAME')
                    # Make sure nothing else has this name.
                    if casefold(generator) != casefold(cmd.name):
                        if core.bayesdb_has_generator(bdb, None, cmd.name):
                            raise BQLError(
                                bdb, 'Name already defined'
                                ' as generator: %s' % (repr(cmd.name), ))
                    # Update bayesdb_generator.  Everything else
                    # refers to it by id.
                    update_generator_sql = '''
                        UPDATE bayesdb_generator SET name = ? WHERE id = ?
                    '''
                    total_changes = bdb._sqlite3.totalchanges()
                    bdb.sql_execute(update_generator_sql,
                                    (cmd.name, generator_id))
                    assert bdb._sqlite3.totalchanges() - total_changes == 1
                    # Remember the new name for subsequent commands.
                    generator = cmd.name
                elif isinstance(cmd, ast.AlterGenGeneric):
                    cmds_generic.append(cmd.command)
                else:
                    assert False, 'Invalid ALTER GENERATOR command: %s' % \
                        (repr(cmd),)
            if cmds_generic:
                modelnos = phrase.modelnos
                modelnos_invalid = None if modelnos is None else [
                    modelno for modelno in modelnos
                    if not core.bayesdb_generator_has_model(
                        bdb, generator_id, modelno)
                ]
                if modelnos_invalid:
                    raise BQLError(
                        bdb, 'No such models in generator %s: %s' %
                        (repr(phrase.generator), repr(modelnos)))
                # Call generic alternations on the backend.
                backend = core.bayesdb_generator_backend(bdb, generator_id)
                backend.alter(bdb, generator_id, modelnos, cmds_generic)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.InitModels):
        if not core.bayesdb_has_generator(bdb, None, phrase.generator):
            raise BQLError(bdb, 'No such generator: %s' % (phrase.generator, ))
        generator_id = core.bayesdb_get_generator(bdb, None, phrase.generator)
        modelnos = range(phrase.nmodels)

        with bdb.savepoint():
            # Find the model numbers.  Omit existing ones for
            # ifnotexists; reject existing ones otherwise.
            if phrase.ifnotexists:
                modelnos = set(modelno for modelno in modelnos
                               if not core.bayesdb_generator_has_model(
                                   bdb, generator_id, modelno))
            else:
                existing = set(modelno for modelno in modelnos
                               if core.bayesdb_generator_has_model(
                                   bdb, generator_id, modelno))
                if 0 < len(existing):
                    raise BQLError(
                        bdb, 'Generator %s already has models: %s' %
                        (repr(phrase.generator), sorted(existing)))

            # Stop now if there's nothing to initialize.
            if len(modelnos) == 0:
                return

            # Create the bayesdb_generator_model records.
            modelnos = sorted(modelnos)
            insert_model_sql = '''
                INSERT INTO bayesdb_generator_model
                    (generator_id, modelno)
                    VALUES (:generator_id, :modelno)
            '''
            for modelno in modelnos:
                bdb.sql_execute(insert_model_sql, {
                    'generator_id': generator_id,
                    'modelno': modelno,
                })

            # Do backend-specific initialization.
            backend = core.bayesdb_generator_backend(bdb, generator_id)
            backend.initialize_models(bdb, generator_id, modelnos)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.AnalyzeModels):
        # WARNING: It is the backend's responsibility to work in a
        # transaction.
        #
        # WARNING: It is the backend's responsibility to update the
        # iteration count in bayesdb_generator_model records.
        #
        # We do this so that the backend can save incremental
        # progress in case of ^C in the middle.
        #
        # XXX Put these warning somewhere more appropriate.
        if not core.bayesdb_has_generator(bdb, None, phrase.generator):
            raise BQLError(bdb, 'No such generator: %s' % (phrase.generator, ))
        generator_id = core.bayesdb_get_generator(bdb, None, phrase.generator)
        backend = core.bayesdb_generator_backend(bdb, generator_id)
        # XXX Should allow parameters for iterations and ckpt/iter.
        backend.analyze_models(bdb,
                               generator_id,
                               modelnos=phrase.modelnos,
                               iterations=phrase.iterations,
                               max_seconds=phrase.seconds,
                               ckpt_iterations=phrase.ckpt_iterations,
                               ckpt_seconds=phrase.ckpt_seconds,
                               program=phrase.program)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropModels):
        with bdb.savepoint():
            generator_id = core.bayesdb_get_generator(bdb, None,
                                                      phrase.generator)
            backend = core.bayesdb_generator_backend(bdb, generator_id)
            modelnos = None
            if phrase.modelnos is not None:
                lookup_model_sql = '''
                    SELECT COUNT(*) FROM bayesdb_generator_model
                        WHERE generator_id = :generator_id
                        AND modelno = :modelno
                '''
                modelnos = sorted(list(phrase.modelnos))
                for modelno in modelnos:
                    cursor = bdb.sql_execute(lookup_model_sql, {
                        'generator_id': generator_id,
                        'modelno': modelno,
                    })
                    if cursor_value(cursor) == 0:
                        raise BQLError(
                            bdb, 'No such model'
                            ' in generator %s: %s' %
                            (repr(phrase.generator), repr(modelno)))
            backend.drop_models(bdb, generator_id, modelnos=modelnos)
            if modelnos is None:
                drop_models_sql = '''
                    DELETE FROM bayesdb_generator_model WHERE generator_id = ?
                '''
                bdb.sql_execute(drop_models_sql, (generator_id, ))
            else:
                drop_model_sql = '''
                    DELETE FROM bayesdb_generator_model
                        WHERE generator_id = :generator_id
                        AND modelno = :modelno
                '''
                for modelno in modelnos:
                    bdb.sql_execute(drop_model_sql, {
                        'generator_id': generator_id,
                        'modelno': modelno,
                    })
        return empty_cursor(bdb)

    if isinstance(phrase, ast.Regress):
        # Retrieve the population.
        if not core.bayesdb_has_population(bdb, phrase.population):
            raise BQLError(bdb,
                           'No such population: %r' % (phrase.population, ))
        population_id = core.bayesdb_get_population(bdb, phrase.population)
        # Retrieve the generator
        generator_id = None
        if phrase.generator:
            if not core.bayesdb_has_generator(bdb, population_id,
                                              phrase.generator):
                raise BQLError(bdb,
                               'No such generator: %r' % (phrase.generator, ))
            generator_id = core.bayesdb_get_generator(bdb, population_id,
                                                      phrase.generator)
        # Retrieve the target variable.
        if not core.bayesdb_has_variable(bdb, population_id, None,
                                         phrase.target):
            raise BQLError(bdb, 'No such variable: %r' % (phrase.target, ))
        colno_target = core.bayesdb_variable_number(bdb, population_id, None,
                                                    phrase.target)
        stattype = core.bayesdb_variable_stattype(bdb, population_id,
                                                  generator_id, colno_target)
        if stattype != 'numerical':
            raise BQLError(
                bdb,
                'Target variable is not numerical: %r' % (phrase.target, ))
        # Build the given variables.
        if any(isinstance(col, ast.SelColAll) for col in phrase.givens):
            # Using * is not allowed to be mixed with other variables.
            if len(phrase.givens) > 1:
                raise BQLError(bdb, 'Cannot use (*) with other givens.')
            colno_givens = core.bayesdb_variable_numbers(
                bdb, population_id, None)
        else:
            if any(isinstance(col, ast.SelColSub) for col in phrase.givens):
                # Subexpression needs special compiling.
                out = compiler.Output(n_numpar, nampar_map, bindings)
                bql_compiler = compiler.BQLCompiler_None()
                givens = compiler.expand_select_columns(
                    bdb, phrase.givens, True, bql_compiler, out)
            else:
                givens = phrase.givens
            colno_givens = [
                core.bayesdb_variable_number(bdb, population_id, None,
                                             given.expression.column)
                for given in givens
            ]
        # Build the arguments to bqlfn.bayesdb_simulate.
        colno_givens_unique = set(colno for colno in colno_givens
                                  if colno != colno_target)
        if len(colno_givens_unique) == 0:
            raise BQLError(bdb, 'No matching given columns.')
        constraints = []
        colnos = [colno_target] + list(colno_givens_unique)
        nsamp = 100 if phrase.nsamp is None else phrase.nsamp.value.value
        modelnos = None if phrase.modelnos is None else str(phrase.modelnos)
        rows = bqlfn.bayesdb_simulate(bdb,
                                      population_id,
                                      generator_id,
                                      modelnos,
                                      constraints,
                                      colnos,
                                      numpredictions=nsamp)
        # Retrieve the stattypes.
        stattypes = [
            core.bayesdb_variable_stattype(bdb, population_id, generator_id,
                                           colno_given)
            for colno_given in colno_givens_unique
        ]
        # Separate the target values from the given values.
        target_values = [row[0] for row in rows]
        given_values = [row[1:] for row in rows]
        given_names = [
            core.bayesdb_variable_name(bdb, population_id, generator_id, given)
            for given in colno_givens_unique
        ]
        # Compute the coefficients. The import to regress_ols is here since the
        # feature depends on pandas + sklearn, so avoid module-wide import.
        from bayeslite.regress import regress_ols
        coefficients = regress_ols(target_values, given_values, given_names,
                                   stattypes)
        # Store the results in a winder.
        temptable = bdb.temp_table_name()
        qtt = sqlite3_quote_name(temptable)
        out = compiler.Output(0, {}, {})
        out.winder(
            '''
            CREATE TEMP TABLE %s (variable TEXT, coefficient REAL);
        ''' % (qtt, ), ())
        for variable, coef in coefficients:
            out.winder(
                '''
                INSERT INTO %s VALUES (?, ?)
            ''' % (qtt), (
                    variable,
                    coef,
                ))
        out.write('SELECT * FROM %s ORDER BY variable' % (qtt, ))
        out.unwinder('DROP TABLE %s' % (qtt, ), ())
        winders, unwinders = out.getwindings()
        return execute_wound(bdb, winders, unwinders, out.getvalue(),
                             out.getbindings())

    assert False  # XXX
Esempio n. 18
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 def generator_depprob(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     depprob_list = backend.column_dependence_probability(
         bdb, generator_id, modelnos, colno0, colno1)
     return stats.arithmetic_mean(depprob_list)
Esempio n. 19
0
def execute_phrase(bdb, phrase, bindings=()):
    """Execute the BQL AST phrase `phrase` and return a cursor of results."""
    if isinstance(phrase, ast.Parametrized):
        n_numpar = phrase.n_numpar
        nampar_map = phrase.nampar_map
        phrase = phrase.phrase
        assert 0 < n_numpar
    else:
        n_numpar = 0
        nampar_map = None
        # Ignore extraneous bindings.  XXX Bad idea?

    if ast.is_query(phrase):
        # Compile the query in the transaction in case we need to
        # execute subqueries to determine column lists.  Compiling is
        # a quick tree descent, so this should be fast.
        out = compiler.Output(n_numpar, nampar_map, bindings)
        with bdb.savepoint():
            compiler.compile_query(bdb, phrase, out)
        winders, unwinders = out.getwindings()
        return execute_wound(bdb, winders, unwinders, out.getvalue(),
            out.getbindings())

    if isinstance(phrase, ast.Begin):
        txn.bayesdb_begin_transaction(bdb)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.Rollback):
        txn.bayesdb_rollback_transaction(bdb)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.Commit):
        txn.bayesdb_commit_transaction(bdb)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.CreateTabAs):
        assert ast.is_query(phrase.query)
        with bdb.savepoint():
            if core.bayesdb_has_table(bdb, phrase.name):
                if phrase.ifnotexists:
                    return empty_cursor(bdb)
                else:
                    raise BQLError(bdb,
                        'Name already defined as table: %s' %
                        (repr(phrase.name),))
            out = compiler.Output(n_numpar, nampar_map, bindings)
            qt = sqlite3_quote_name(phrase.name)
            temp = 'TEMP ' if phrase.temp else ''
            ifnotexists = 'IF NOT EXISTS ' if phrase.ifnotexists else ''
            out.write('CREATE %sTABLE %s%s AS ' % (temp, ifnotexists, qt))
            compiler.compile_query(bdb, phrase.query, out)
            winders, unwinders = out.getwindings()
            with compiler.bayesdb_wind(bdb, winders, unwinders):
                bdb.sql_execute(out.getvalue(), out.getbindings())
        return empty_cursor(bdb)

    if isinstance(phrase, ast.CreateTabCsv):
        with bdb.savepoint():
            table_exists = core.bayesdb_has_table(bdb, phrase.name)
            if table_exists:
                if phrase.ifnotexists:
                    return empty_cursor(bdb)
                else:
                    raise BQLError(bdb, 'Table already exists: %s' %
                        (repr(phrase.name),))
            bayesdb_read_csv_file(
                bdb, phrase.name, phrase.csv, header=True, create=True)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropTab):
        with bdb.savepoint():
            sql = 'SELECT COUNT(*) FROM bayesdb_population WHERE tabname = ?'
            cursor = bdb.sql_execute(sql, (phrase.name,))
            if 0 < cursor_value(cursor):
                raise BQLError(bdb, 'Table still in use by populations: %s' %
                    (repr(phrase.name),))
            bdb.sql_execute('DELETE FROM bayesdb_column WHERE tabname = ?',
                (phrase.name,))
            ifexists = 'IF EXISTS ' if phrase.ifexists else ''
            qt = sqlite3_quote_name(phrase.name)
            return bdb.sql_execute('DROP TABLE %s%s' % (ifexists, qt))

    if isinstance(phrase, ast.AlterTab):
        with bdb.savepoint():
            table = phrase.table
            if not core.bayesdb_has_table(bdb, table):
                raise BQLError(bdb, 'No such table: %s' % (repr(table),))
            for cmd in phrase.commands:
                if isinstance(cmd, ast.AlterTabRenameTab):
                    # If the names differ only in case, we have to do
                    # some extra work because SQLite will reject the
                    # table rename.  Note that we may even have table
                    # == cmd.name here, but if the stored table name
                    # differs in case from cmd.name, we want to update
                    # it anyway.
                    if casefold(table) == casefold(cmd.name):
                        # Go via a temporary table.
                        temp = table + '_temp'
                        while core.bayesdb_has_table(bdb, temp):
                            temp += '_temp'
                        rename_table(bdb, table, temp)
                        rename_table(bdb, temp, cmd.name)
                    else:
                        # Make sure nothing else has this name and
                        # rename it.
                        if core.bayesdb_has_table(bdb, cmd.name):
                            raise BQLError(bdb,
                                'Name already defined as table: %s'
                                % (repr(cmd.name),))
                        rename_table(bdb, table, cmd.name)
                    # If table has implicit population, rename it too.
                    if core.bayesdb_table_has_implicit_population(
                                bdb, cmd.name):
                        populations = \
                            core.bayesdb_table_populations(bdb, cmd.name)
                        assert len(populations) == 1
                        population_name = core.bayesdb_population_name(
                            bdb, populations[0])
                        qt = sqlite3_quote_name(cmd.name)
                        qp = sqlite3_quote_name(population_name)
                        bdb.execute('ALTER POPULATION %s RENAME TO %s'
                            % (qp, qt))
                    # Remember the new name for subsequent commands.
                    table = cmd.name
                elif isinstance(cmd, ast.AlterTabRenameCol):
                    # XXX Need to deal with this in the compiler.
                    raise NotImplementedError('Renaming columns'
                        ' not yet implemented.')
                    # Make sure the old name exist and the new name does not.
                    old_folded = casefold(cmd.old)
                    new_folded = casefold(cmd.new)
                    if old_folded != new_folded:
                        if not core.bayesdb_table_has_column(bdb, table,
                                cmd.old):
                            raise BQLError(bdb, 'No such column in table %s'
                                ': %s' %
                                (repr(table), repr(cmd.old)))
                        if core.bayesdb_table_has_column(bdb, table, cmd.new):
                            raise BQLError(bdb, 'Column already exists'
                                ' in table %s: %s' %
                                (repr(table), repr(cmd.new)))
                    # Update bayesdb_column.  Everything else refers
                    # to columns by (tabname, colno) pairs rather than
                    # by names.
                    update_column_sql = '''
                        UPDATE bayesdb_column SET name = :new
                            WHERE tabname = :table AND name = :old
                    '''
                    total_changes = bdb._sqlite3.totalchanges()
                    bdb.sql_execute(update_column_sql, {
                        'table': table,
                        'old': cmd.old,
                        'new': cmd.new,
                    })
                    assert bdb._sqlite3.totalchanges() - total_changes == 1
                    # ...except backends may have the (case-folded) name cached.
                    if old_folded != new_folded:
                        populations_sql = '''
                            SELECT id FROM bayesdb_population WHERE tabname = ?
                        '''
                        cursor = bdb.sql_execute(populations_sql, (table,))
                        generators = [
                            core.bayesdb_population_generators(
                                bdb, population_id)
                            for (population_id,) in cursor
                        ]
                        for generator_id in set(generators):
                            backend = core.bayesdb_generator_backend(bdb,
                                generator_id)
                            backend.rename_column(bdb, generator_id,
                                old_folded, new_folded)
                else:
                    assert False, 'Invalid alter table command: %s' % \
                        (cmd,)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.GuessSchema):
        if not core.bayesdb_has_table(bdb, phrase.table):
            raise BQLError(bdb, 'No such table : %s' % phrase.table)
        out = compiler.Output(0, {}, {})
        with bdb.savepoint():
            qt = sqlite3_quote_name(phrase.table)
            temptable = bdb.temp_table_name()
            qtt = sqlite3_quote_name(temptable)
            cursor = bdb.sql_execute('SELECT * FROM %s' % (qt,))
            column_names = [d[0] for d in cursor.description]
            rows = cursor.fetchall()
            stattypes = bayesdb_guess_stattypes(column_names, rows)
            distinct_value_counts = [
                len(set([row[i] for row in rows]))
                for i in range(len(column_names))
            ]
            out.winder('''
                CREATE TEMP TABLE %s (
                    column TEXT,
                    stattype TEXT,
                    num_distinct INTEGER,
                    reason TEXT
                )
            ''' % (qtt,), ())
            for cn, st, ct in zip(column_names, stattypes, distinct_value_counts):
                out.winder('''
                    INSERT INTO %s VALUES (?, ?, ?, ?)
                ''' % (qtt), (cn, st[0], ct, st[1]))
            out.write('SELECT * FROM %s' % (qtt,))
            out.unwinder('DROP TABLE %s' % (qtt,), ())
        winders, unwinders = out.getwindings()
        return execute_wound(
            bdb, winders, unwinders, out.getvalue(), out.getbindings())

    if isinstance(phrase, ast.CreatePop):
        with bdb.savepoint():
            _create_population(bdb, phrase)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropPop):
        with bdb.savepoint():
            if not core.bayesdb_has_population(bdb, phrase.name):
                if phrase.ifexists:
                    return empty_cursor(bdb)
                raise BQLError(bdb, 'No such population: %r' % (phrase.name,))
            population_id = core.bayesdb_get_population(bdb, phrase.name)
            generator_ids = core.bayesdb_population_generators(
                bdb, population_id)
            if generator_ids:
                generators = [core.bayesdb_generator_name(bdb, gid)
                    for gid in generator_ids]
                raise BQLError(bdb, 'Population %r still has generators: %r' %
                    (phrase.name, generators))
            # XXX helpful error checking if generators still exist
            # XXX check change counts
            bdb.sql_execute('''
                DELETE FROM bayesdb_variable WHERE population_id = ?
            ''', (population_id,))
            bdb.sql_execute('''
                DELETE FROM bayesdb_population WHERE id = ?
            ''', (population_id,))
        return empty_cursor(bdb)

    if isinstance(phrase, ast.AlterPop):
        with bdb.savepoint():
            population = phrase.population
            if not core.bayesdb_has_population(bdb, population):
                raise BQLError(bdb, 'No such population: %s' %
                    (repr(population),))
            population_id = core.bayesdb_get_population(bdb, population)
            for cmd in phrase.commands:
                if isinstance(cmd, ast.AlterPopRenamePop):
                    table = core.bayesdb_population_table(bdb, population_id)
                    # Prevent renaming of implicit population directly, unless
                    # being called by ast.AlterTabRenameTab in which case the
                    # table name and population name will not be matching.
                    if core.bayesdb_population_is_implicit(bdb, population_id) \
                            and casefold(population) == casefold(table):
                        raise BQLError(bdb, 'Cannot rename implicit'
                            'population %s; rename base table instead'
                            % (population,))
                    # Make sure nothing else has this name.
                    if casefold(population) != casefold(cmd.name):
                        if core.bayesdb_has_population(bdb, cmd.name):
                            raise BQLError(bdb,
                                'Name already defined as population' ': %s'
                                % (repr(cmd.name),))
                    # Update bayesdb_population.  Everything else
                    # refers to it by id.
                    update_generator_sql = '''
                        UPDATE bayesdb_population SET name = ? WHERE id = ?
                    '''
                    total_changes = bdb._sqlite3.totalchanges()
                    bdb.sql_execute(update_generator_sql,
                        (cmd.name, population_id))
                    assert bdb._sqlite3.totalchanges() - total_changes == 1
                    # If population has implicit generator, rename it too.
                    if core.bayesdb_population_has_implicit_generator(
                            bdb, population_id):
                        generators = core.bayesdb_population_generators(
                            bdb, population_id)
                        assert len(generators) == 1
                        generator_name = core.bayesdb_generator_name(
                            bdb, generators[0])
                        qp = sqlite3_quote_name(cmd.name)
                        qg = sqlite3_quote_name(generator_name)
                        bdb.execute('ALTER GENERATOR %s RENAME TO %s'
                            % (qg, qp,))
                    # Remember the new name for subsequent commands.
                    population = cmd.name
                elif isinstance(cmd, ast.AlterPopAddVar):
                    # Ensure column exists in base table.
                    table = core.bayesdb_population_table(bdb, population_id)
                    if not core.bayesdb_table_has_column(
                            bdb, table, cmd.name):
                        raise BQLError(bdb,
                            'No such variable in base table: %s'
                            % (cmd.name))
                    # Ensure variable not already in population.
                    if core.bayesdb_has_variable(
                            bdb, population_id, None, cmd.name):
                        raise BQLError(bdb,
                            'Variable already in population: %s'
                            % (cmd.name))
                    # Ensure there is at least observation in the column.
                    qt = sqlite3_quote_name(table)
                    qc = sqlite3_quote_name(cmd.name)
                    cursor = bdb.sql_execute(
                        'SELECT COUNT(*) FROM %s WHERE %s IS NOT NULL' %
                        (qt, qc))
                    if cursor_value(cursor) == 0:
                        raise BQLError(bdb,
                            'Cannot add variable without any values: %s'
                            % (cmd.name))
                    # If stattype is None, guess.
                    if cmd.stattype is None:
                        cursor = bdb.sql_execute(
                            'SELECT %s FROM %s' % (qc, qt))
                        rows = cursor.fetchall()
                        [stattype, reason] = bayesdb_guess_stattypes(
                            [cmd.name], rows)[0]
                        # Fail if trying to model a key.
                        if stattype == 'key':
                            raise BQLError(bdb,
                                'Values in column %s appear to be keys.'
                                % (cmd.name,))
                        # Fail if cannot determine a stattype.
                        elif stattype == 'ignore':
                            raise BQLError(bdb,
                                'Failed to determine a stattype for %s, '
                                'please specify one manually.' % (cmd.name,))
                    # If user specified stattype, ensure it exists.
                    elif not core.bayesdb_has_stattype(bdb, cmd.stattype):
                        raise BQLError(bdb,
                            'Invalid stattype: %s' % (cmd.stattype))
                    else:
                        stattype = cmd.stattype
                    # Check that strings are not being modeled as numerical.
                    if stattype == 'numerical' \
                            and _column_contains_string(bdb, table, cmd.name):
                        raise BQLError(bdb,
                            'Numerical column contains string values: %r '
                            % (qc,))
                    with bdb.savepoint():
                        # Add the variable to the population.
                        core.bayesdb_add_variable(
                            bdb, population_id, cmd.name, stattype)
                        colno = core.bayesdb_variable_number(
                            bdb, population_id, None, cmd.name)
                        # Add the variable to each (initialized) generator in
                        # the population.
                        generator_ids = filter(
                            lambda g: core.bayesdb_generator_modelnos(bdb, g),
                            core.bayesdb_population_generators(
                                bdb, population_id),
                        )
                        for generator_id in generator_ids:
                            backend = core.bayesdb_generator_backend(
                                bdb, generator_id)
                            backend.add_column(bdb, generator_id, colno)
                elif isinstance(cmd, ast.AlterPopStatType):
                    # Check the no generators are defined for this population.
                    generators = core.bayesdb_population_generators(
                        bdb, population_id)
                    if generators:
                        raise BQLError(bdb,
                            'Cannot update statistical types for population '
                            '%s, it has generators: %s'
                            % (repr(population), repr(generators),))
                    # Check all the variables are in the population.
                    unknown = [
                        c for c in cmd.names if not
                        core.bayesdb_has_variable(bdb, population_id, None, c)
                    ]
                    if unknown:
                        raise BQLError(bdb,
                            'No such variables in population: %s'
                            % (repr(unknown)))
                    # Check the statistical type is valid.
                    if not core.bayesdb_has_stattype(bdb, cmd.stattype):
                        raise BQLError(bdb,
                            'Invalid statistical type: %r'
                            % (repr(cmd.stattype),))
                    # Check that strings are not being modeled as numerical.
                    if cmd.stattype == 'numerical':
                        table = core.bayesdb_population_table(
                            bdb, population_id)
                        numerical_string_vars = [
                            col for col in cmd.names
                            if _column_contains_string(bdb, table, col)
                        ]
                        if numerical_string_vars:
                            raise BQLError(bdb,
                                'Columns with string values modeled as '
                                'numerical: %r' % (numerical_string_vars,))
                    # Perform the stattype update.
                    colnos = [
                        core.bayesdb_variable_number(
                            bdb, population_id, None, c) for c in cmd.names
                    ]
                    qcolnos = ','.join('%d' % (colno,) for colno in colnos)
                    update_stattype_sql = '''
                        UPDATE bayesdb_variable SET stattype = ?
                            WHERE population_id = ? AND colno IN (%s)
                    ''' % (qcolnos,)
                    bdb.sql_execute(
                        update_stattype_sql,
                        (casefold(cmd.stattype), population_id,))
                else:
                    assert False, 'Invalid ALTER POPULATION command: %s' % \
                        (repr(cmd),)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.CreateGen):
        # Find the population.
        if not core.bayesdb_has_population(bdb, phrase.population):
            raise BQLError(bdb, 'No such population: %r' %
                (phrase.population,))
        population_id = core.bayesdb_get_population(bdb, phrase.population)

        # Find the backend, or use the default.
        backend_name = phrase.backend
        if phrase.backend is None:
            backend_name = 'cgpm'
        if backend_name not in bdb.backends:
            raise BQLError(bdb, 'No such backend: %s' %
                (repr(backend_name),))
        backend = bdb.backends[backend_name]

        # Retrieve the (possibility implicit) generator name.
        generator_name = phrase.name or phrase.population
        implicit = 1 if phrase.name is None else 0

        with bdb.savepoint():
            if core.bayesdb_has_generator(bdb, population_id, generator_name):
                if not phrase.ifnotexists:
                    raise BQLError(
                        bdb, 'Name already defined as generator: %s' %
                        (repr(generator_name),))
            else:
                # Insert a record into bayesdb_generator and get the
                # assigned id.
                bdb.sql_execute('''
                    INSERT INTO bayesdb_generator
                        (name, population_id, backend, implicit)
                        VALUES (?, ?, ?, ?)
                ''', (generator_name, population_id, backend.name(), implicit))
                generator_id = core.bayesdb_get_generator(
                    bdb, population_id, generator_name)
                # Do any backend-specific initialization.
                backend.create_generator(bdb, generator_id, phrase.schema)

        # All done.  Nothing to return.
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropGen):
        with bdb.savepoint():
            if not core.bayesdb_has_generator(bdb, None, phrase.name):
                if phrase.ifexists:
                    return empty_cursor(bdb)
                raise BQLError(bdb, 'No such generator: %s' %
                    (repr(phrase.name),))
            generator_id = core.bayesdb_get_generator(bdb, None, phrase.name)
            backend = core.bayesdb_generator_backend(bdb, generator_id)

            # Backend-specific destruction.
            backend.drop_generator(bdb, generator_id)

            # Drop latent variables, models, and, finally, generator.
            drop_columns_sql = '''
                DELETE FROM bayesdb_variable WHERE generator_id = ?
            '''
            bdb.sql_execute(drop_columns_sql, (generator_id,))
            drop_model_sql = '''
                DELETE FROM bayesdb_generator_model WHERE generator_id = ?
            '''
            bdb.sql_execute(drop_model_sql, (generator_id,))
            drop_generator_sql = '''
                DELETE FROM bayesdb_generator WHERE id = ?
            '''
            bdb.sql_execute(drop_generator_sql, (generator_id,))
        return empty_cursor(bdb)

    if isinstance(phrase, ast.AlterGen):
        with bdb.savepoint():
            generator = phrase.generator
            if not core.bayesdb_has_generator(bdb, None, generator):
                raise BQLError(bdb, 'No such generator: %s' %
                    (repr(generator),))
            generator_id = core.bayesdb_get_generator(bdb, None, generator)
            cmds_generic = []
            for cmd in phrase.commands:
                if isinstance(cmd, ast.AlterGenRenameGen):
                    population_id = core.bayesdb_generator_population(
                        bdb, generator_id)
                    population = core.bayesdb_population_name(
                        bdb, population_id)
                    # Prevent renaming of implicit generator directly, unless
                    # being called by ast.AlterPopRenamePop in which case the
                    # population name and generator name will not be matching.
                    if core.bayesdb_population_is_implicit(bdb, generator_id) \
                            and casefold(generator) == casefold(population):
                        raise BQLError(bdb, 'Cannot rename implicit '
                            'generator; rename base population instead')
                    # Disable modelnos with AlterGenRenameGen.
                    if phrase.modelnos is not None:
                        raise BQLError(bdb, 'Cannot specify models for RENAME')
                    # Make sure nothing else has this name.
                    if casefold(generator) != casefold(cmd.name):
                        if core.bayesdb_has_generator(bdb, None, cmd.name):
                            raise BQLError(bdb, 'Name already defined'
                                ' as generator: %s' %
                                (repr(cmd.name),))
                    # Update bayesdb_generator.  Everything else
                    # refers to it by id.
                    update_generator_sql = '''
                        UPDATE bayesdb_generator SET name = ? WHERE id = ?
                    '''
                    total_changes = bdb._sqlite3.totalchanges()
                    bdb.sql_execute(update_generator_sql,
                        (cmd.name, generator_id))
                    assert bdb._sqlite3.totalchanges() - total_changes == 1
                    # Remember the new name for subsequent commands.
                    generator = cmd.name
                elif isinstance(cmd, ast.AlterGenGeneric):
                    cmds_generic.append(cmd.command)
                else:
                    assert False, 'Invalid ALTER GENERATOR command: %s' % \
                        (repr(cmd),)
            if cmds_generic:
                modelnos = phrase.modelnos
                modelnos_invalid = None if modelnos is None else [
                    modelno for modelno in modelnos if not
                    core.bayesdb_generator_has_model(bdb, generator_id, modelno)
                ]
                if modelnos_invalid:
                    raise BQLError(bdb,
                        'No such models in generator %s: %s' %
                        (repr(phrase.generator), repr(modelnos)))
                # Call generic alternations on the backend.
                backend = core.bayesdb_generator_backend(bdb, generator_id)
                backend.alter(bdb, generator_id, modelnos, cmds_generic)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.InitModels):
        if not core.bayesdb_has_generator(bdb, None, phrase.generator):
            raise BQLError(bdb, 'No such generator: %s' %
                (phrase.generator,))
        generator_id = core.bayesdb_get_generator(bdb, None, phrase.generator)
        modelnos = range(phrase.nmodels)

        with bdb.savepoint():
            # Find the model numbers.  Omit existing ones for
            # ifnotexists; reject existing ones otherwise.
            if phrase.ifnotexists:
                modelnos = set(modelno for modelno in modelnos
                    if not core.bayesdb_generator_has_model(bdb, generator_id,
                        modelno))
            else:
                existing = set(modelno for modelno in modelnos
                    if core.bayesdb_generator_has_model(bdb, generator_id,
                        modelno))
                if 0 < len(existing):
                    raise BQLError(bdb, 'Generator %s already has models: %s' %
                        (repr(phrase.generator), sorted(existing)))

            # Stop now if there's nothing to initialize.
            if len(modelnos) == 0:
                return

            # Create the bayesdb_generator_model records.
            modelnos = sorted(modelnos)
            insert_model_sql = '''
                INSERT INTO bayesdb_generator_model
                    (generator_id, modelno)
                    VALUES (:generator_id, :modelno)
            '''
            for modelno in modelnos:
                bdb.sql_execute(insert_model_sql, {
                    'generator_id': generator_id,
                    'modelno': modelno,
                })

            # Do backend-specific initialization.
            backend = core.bayesdb_generator_backend(bdb, generator_id)
            backend.initialize_models(bdb, generator_id, modelnos)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.AnalyzeModels):
        # WARNING: It is the backend's responsibility to work in a
        # transaction.
        #
        # WARNING: It is the backend's responsibility to update the
        # iteration count in bayesdb_generator_model records.
        #
        # We do this so that the backend can save incremental
        # progress in case of ^C in the middle.
        #
        # XXX Put these warning somewhere more appropriate.
        if not core.bayesdb_has_generator(bdb, None, phrase.generator):
            raise BQLError(bdb, 'No such generator: %s' %
                (phrase.generator,))
        generator_id = core.bayesdb_get_generator(bdb, None, phrase.generator)
        backend = core.bayesdb_generator_backend(bdb, generator_id)
        # XXX Should allow parameters for iterations and ckpt/iter.
        backend.analyze_models(bdb, generator_id,
            modelnos=phrase.modelnos,
            iterations=phrase.iterations,
            max_seconds=phrase.seconds,
            ckpt_iterations=phrase.ckpt_iterations,
            ckpt_seconds=phrase.ckpt_seconds,
            program=phrase.program)
        return empty_cursor(bdb)

    if isinstance(phrase, ast.DropModels):
        with bdb.savepoint():
            generator_id = core.bayesdb_get_generator(
                bdb, None, phrase.generator)
            backend = core.bayesdb_generator_backend(bdb, generator_id)
            modelnos = None
            if phrase.modelnos is not None:
                lookup_model_sql = '''
                    SELECT COUNT(*) FROM bayesdb_generator_model
                        WHERE generator_id = :generator_id
                        AND modelno = :modelno
                '''
                modelnos = sorted(list(phrase.modelnos))
                for modelno in modelnos:
                    cursor = bdb.sql_execute(lookup_model_sql, {
                        'generator_id': generator_id,
                        'modelno': modelno,
                    })
                    if cursor_value(cursor) == 0:
                        raise BQLError(bdb, 'No such model'
                            ' in generator %s: %s' %
                            (repr(phrase.generator), repr(modelno)))
            backend.drop_models(bdb, generator_id, modelnos=modelnos)
            if modelnos is None:
                drop_models_sql = '''
                    DELETE FROM bayesdb_generator_model WHERE generator_id = ?
                '''
                bdb.sql_execute(drop_models_sql, (generator_id,))
            else:
                drop_model_sql = '''
                    DELETE FROM bayesdb_generator_model
                        WHERE generator_id = :generator_id
                        AND modelno = :modelno
                '''
                for modelno in modelnos:
                    bdb.sql_execute(drop_model_sql, {
                        'generator_id': generator_id,
                        'modelno': modelno,
                    })
        return empty_cursor(bdb)

    if isinstance(phrase, ast.Regress):
        # Retrieve the population.
        if not core.bayesdb_has_population(bdb, phrase.population):
            raise BQLError(bdb, 'No such population: %r' % (phrase.population,))
        population_id = core.bayesdb_get_population(bdb, phrase.population)
        # Retrieve the generator
        generator_id = None
        if phrase.generator:
            if not core.bayesdb_has_generator(bdb, population_id,
                    phrase.generator):
                raise BQLError(bdb,
                    'No such generator: %r' % (phrase.generator,))
            generator_id = core.bayesdb_get_generator(
                bdb, population_id, phrase.generator)
        # Retrieve the target variable.
        if not core.bayesdb_has_variable(
                bdb, population_id, None, phrase.target):
            raise BQLError(bdb, 'No such variable: %r' % (phrase.target,))
        colno_target = core.bayesdb_variable_number(
            bdb, population_id, None, phrase.target)
        stattype = core.bayesdb_variable_stattype(bdb, population_id,
            generator_id, colno_target)
        if stattype != 'numerical':
            raise BQLError(bdb,
                'Target variable is not numerical: %r' % (phrase.target,))
        # Build the given variables.
        if any(isinstance(col, ast.SelColAll) for col in phrase.givens):
            # Using * is not allowed to be mixed with other variables.
            if len(phrase.givens) > 1:
                raise BQLError(bdb, 'Cannot use (*) with other givens.')
            colno_givens = core.bayesdb_variable_numbers(
                bdb, population_id, None)
        else:
            if any(isinstance(col, ast.SelColSub) for col in phrase.givens):
                # Subexpression needs special compiling.
                out = compiler.Output(n_numpar, nampar_map, bindings)
                bql_compiler = compiler.BQLCompiler_None()
                givens = compiler.expand_select_columns(
                    bdb, phrase.givens, True, bql_compiler, out)
            else:
                givens = phrase.givens
            colno_givens = [
                core.bayesdb_variable_number(
                    bdb, population_id, None, given.expression.column)
                for given in givens
            ]
        # Build the arguments to bqlfn.bayesdb_simulate.
        colno_givens_unique = set(
            colno for colno in colno_givens if colno!= colno_target
        )
        if len(colno_givens_unique) == 0:
            raise BQLError(bdb, 'No matching given columns.')
        constraints = []
        colnos = [colno_target] + list(colno_givens_unique)
        nsamp = 100 if phrase.nsamp is None else phrase.nsamp.value.value
        modelnos = None if phrase.modelnos is None else str(phrase.modelnos)
        rows = bqlfn.bayesdb_simulate(
            bdb, population_id, generator_id, modelnos, constraints,
            colnos, numpredictions=nsamp)
        # Retrieve the stattypes.
        stattypes = [
            core.bayesdb_variable_stattype(
                bdb, population_id, generator_id, colno_given)
            for colno_given in colno_givens_unique
        ]
        # Separate the target values from the given values.
        target_values = [row[0] for row in rows]
        given_values = [row[1:] for row in rows]
        given_names = [
            core.bayesdb_variable_name(bdb, population_id, generator_id, given)
            for given in colno_givens_unique
        ]
        # Compute the coefficients. The import to regress_ols is here since the
        # feature depends on pandas + sklearn, so avoid module-wide import.
        from bayeslite.regress import regress_ols
        coefficients = regress_ols(
            target_values, given_values, given_names, stattypes)
        # Store the results in a winder.
        temptable = bdb.temp_table_name()
        qtt = sqlite3_quote_name(temptable)
        out = compiler.Output(0, {}, {})
        out.winder('''
            CREATE TEMP TABLE %s (variable TEXT, coefficient REAL);
        ''' % (qtt,), ())
        for variable, coef in coefficients:
            out.winder('''
                INSERT INTO %s VALUES (?, ?)
            ''' % (qtt), (variable, coef,))
        out.write('SELECT * FROM %s ORDER BY variable' % (qtt,))
        out.unwinder('DROP TABLE %s' % (qtt,), ())
        winders, unwinders = out.getwindings()
        return execute_wound(
            bdb, winders, unwinders, out.getvalue(), out.getbindings())

    assert False                # XXX
Esempio n. 20
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 def generator_mutinf(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     return backend.column_mutual_information(
         bdb, generator_id, modelnos, colnos0, colnos1,
         constraints=constraints, numsamples=numsamples)
Esempio n. 21
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    def _cmd_render_crosscat(self, query, sql=None, **kwargs):
        '''Returns a rendering of the specified crosscat state

        Usage: .render_crosscat [options] <generator> <modelno>.

        Options:
            --subsample=<n>
            --width=<w>
            --height=<c>
            --rowlabels=<colname>
            --progress=[True|False]
            --yticklabeslize=<fontsize>
            --xticklabeslize=<fontsize>

        The allowable fontsize strings are:
            xx-small, x-small, # small, medium, large, x-large, xx-large
        '''
        tokens = query.split()
        if len(tokens) != 2:
            self.write_stderr('Usage: .render_crosscat <generator> <modelno>')
            return
        generator = tokens[0]
        modelno = int(tokens[1])
        if not bayesdb_has_generator(self._bdb, None, generator):
            self.write_stderr('No such generator: %s.' % (generator, ))
            return
        generator_id = bayesdb_get_generator(self._bdb, None, generator)
        population_id = bayesdb_generator_population(self._bdb, generator_id)
        backend = bayesdb_generator_backend(self._bdb, generator_id)
        if backend.name() != 'cgpm':
            self.write_stderr('.render_crosscat requires generator from the '
                              'cgpm backend')
            return
        engine = backend._engine(self._bdb, generator_id)
        cursor = self._bdb.sql_execute(
            '''
            SELECT cgpm_modelno FROM bayesdb_cgpm_modelno
            WHERE generator_id = ? AND modelno = ?
        ''', (
                generator_id,
                modelno,
            ))
        cgpm_modelno = cursor_value(cursor, nullok=True)
        if cgpm_modelno is None:
            self.write_stderr('No such model number: %d.' % (modelno, ))
            return
        state = engine.get_state(cgpm_modelno)
        row_names = None
        row_index_column = kwargs.get('rowlabels', None)
        if row_index_column is not None:
            table_name = bayesdb_generator_table(self._bdb, generator_id)
            qt = bql_quote_name(table_name)
            qc = bql_quote_name(row_index_column)
            cursor = self._bdb.sql_execute(
                '''
                SELECT %s FROM %s WHERE oid IN (
                    SELECT table_rowid FROM bayesdb_cgpm_individual
                    WHERE generator_id = ?
                )
            ''' % (qc, qt), (generator_id, ))
            row_names = [c[0] for c in cursor]
        if 'progress' in kwargs:
            sys.stdout.write('Creating figure...\n')
        import cgpm.utils.render
        if 'variable' not in kwargs:
            # Plot the entire state.
            col_names = [
                bayesdb_variable_name(self._bdb, population_id, None, colno)
                for colno in state.outputs
            ]
            fig, _ax = cgpm.utils.render.viz_state(state,
                                                   col_names=col_names,
                                                   row_names=row_names,
                                                   **kwargs)
        else:
            # Plot the view of the requested variable.
            varno = bayesdb_variable_number(self._bdb, population_id,
                                            generator_id, kwargs['variable'])
            view = state.view_for(varno)
            col_names = [
                bayesdb_variable_name(self._bdb, population_id, None, colno)
                for colno in view.outputs[1:]
            ]
            fig, _ax = cgpm.utils.render.viz_view(view,
                                                  col_names=col_names,
                                                  row_names=row_names,
                                                  **kwargs)
        (width, height) = fig.get_size_inches()
        if 'width' in kwargs:
            width = float(kwargs['width'])
            fig.set_size_inches(width, height)
        if 'height' in kwargs:
            height = float(kwargs['height'])
            fig.set_size_inches(width, height)
        if 'progress' in kwargs:
            sys.stdout.write('Rendering figure...\n')
Esempio n. 22
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 def generator_depprob(generator_id):
     backend = core.bayesdb_generator_backend(bdb, generator_id)
     depprob_list = backend.column_dependence_probability(
         bdb, generator_id, modelnos, colno0, colno1)
     return stats.arithmetic_mean(depprob_list)