def column_map(tables, columns):
"""
Take a list of tables and a list of column names and resolve which
columns come from which table.
Parameters
----------
tables : sequence of _DataFrameWrapper or _TableFuncWrapper
Could also be sequence of modified pandas.DataFrames, the important
thing is that they have ``.name`` and ``.columns`` attributes.
columns : sequence of str
The column names of interest.
Returns
-------
col_map : dict
Maps table names to lists of column names.
"""
if not columns:
return {t.name: None for t in tables}
columns = set(columns)
colmap = {t.name: list(set(t.columns).intersection(columns)) for t in tables}
foundcols = tz.reduce(lambda x, y: x.union(y), (set(v) for v in colmap.values()))
if foundcols != columns:
raise RuntimeError('Not all required columns were found. '
'Missing: {}'.format(list(columns - foundcols)))
return colmap
def column_map(tables, columns):
"""
Take a list of tables and a list of column names and resolve which
columns come from which table.
Parameters
----------
tables : sequence of _DataFrameWrapper or _TableFuncWrapper
Could also be sequence of modified pandas.DataFrames, the important
thing is that they have ``.name`` and ``.columns`` attributes.
columns : sequence of str
The column names of interest.
Returns
-------
col_map : dict
Maps table names to lists of column names.
"""
if not columns:
return {t.name: None for t in tables}
columns = set(columns)
colmap = {
t.name: list(set(t.columns).intersection(columns))
for t in tables
}
foundcols = tz.reduce(lambda x, y: x.union(y),
(set(v) for v in colmap.values()))
if foundcols != columns:
raise RuntimeError('Not all required columns were found. '
'Missing: {}'.format(list(columns - foundcols)))
return colmap
def column_list(tables, columns):
"""
Take a list of tables and a list of column names and return the columns
that are present in the tables.
Parameters
----------
tables : sequence of _DataFrameWrapper or _TableFuncWrapper
Could also be sequence of modified pandas.DataFrames, the important
thing is that they have ``.name`` and ``.columns`` attributes.
columns : sequence of str
The column names of interest.
Returns
-------
cols : list
Lists of column names available in the tables.
"""
columns = set(columns)
foundcols = tz.reduce(lambda x, y: x.union(y), (set(t.columns) for t in tables))
return list(columns.intersection(foundcols))
def column_list(tables, columns):
"""
Take a list of tables and a list of column names and return the columns
that are present in the tables.
Parameters
----------
tables : sequence of _DataFrameWrapper or _TableFuncWrapper
Could also be sequence of modified pandas.DataFrames, the important
thing is that they have ``.name`` and ``.columns`` attributes.
columns : sequence of str
The column names of interest.
Returns
-------
cols : list
Lists of column names available in the tables.
"""
columns = set(columns)
foundcols = tz.reduce(lambda x, y: x.union(y),
(set(t.columns) for t in tables))
return list(columns.intersection(foundcols))
