def _fit(self, X, y, groups, parameter_iterable):
"""Actual fitting, performing the search over parameters."""
X, y, groups = indexable(X, y, groups)
cv = check_cv(self.cv, y, classifier=True)
n_splits = cv.get_n_splits(X, y, groups)
if self.verbose > 0 and isinstance(parameter_iterable, Sized):
n_candidates = len(parameter_iterable)
LOG.info("Fitting %d folds for each of %d candidates, totalling"
" %d fits", n_splits, n_candidates, n_candidates * n_splits)
pre_dispatch = self.pre_dispatch
cv_iter = list(cv.split(X, y, groups))
out = Parallel(
n_jobs=self.n_jobs, verbose=self.verbose,
pre_dispatch=pre_dispatch
)(delayed(_model_fit_and_score)(
estimator, X, y, self.scoring, train, test, self.verbose, parameters,
fit_params=self.fit_params,
return_train_score=self.return_train_score,
return_n_test_samples=True,
return_times=True, return_parameters=True,
error_score=self.error_score)
for estimator, parameters in parameter_iterable
for train, test in cv_iter)
# if one choose to see train score, "out" will contain train score info
if self.return_train_score:
(train_scores, test_scores, test_sample_counts,
fit_time, score_time, parameters) = zip(*out)
else:
(test_scores, test_sample_counts,
fit_time, score_time, parameters) = zip(*out)
candidate_params = parameters[::n_splits]
n_candidates = len(candidate_params)
results = dict()
def _store(key_name, array, weights=None, splits=False, rank=False):
"""A small helper to store the scores/times to the cv_results_"""
array = np.array(array, dtype=np.float64).reshape(n_candidates,
n_splits)
if splits:
for split_i in range(n_splits):
results["split%d_%s"
% (split_i, key_name)] = array[:, split_i]
array_means = np.average(array, axis=1, weights=weights)
results['mean_%s' % key_name] = array_means
# Weighted std is not directly available in numpy
array_stds = np.sqrt(np.average((array -
array_means[:, np.newaxis]) ** 2,
axis=1, weights=weights))
results['std_%s' % key_name] = array_stds
if rank:
results["rank_%s" % key_name] = np.asarray(
rankdata(-array_means, method='min'), dtype=np.int32)
# Computed the (weighted) mean and std for test scores alone
# NOTE test_sample counts (weights) remain the same for all candidates
test_sample_counts = np.array(test_sample_counts[:n_splits],
dtype=np.int)
_store('test_score', test_scores, splits=True, rank=True,
weights=test_sample_counts if self.iid else None)
if self.return_train_score:
_store('train_score', train_scores, splits=True)
_store('fit_time', fit_time)
_store('score_time', score_time)
best_index = np.flatnonzero(results["rank_test_score"] == 1)[0]
best_parameters = candidate_params[best_index][1]
# Use one MaskedArray and mask all the places where the param is not
# applicable for that candidate. Use defaultdict as each candidate may
# not contain all the params
param_results = defaultdict(partial(MaskedArray,
np.empty(n_candidates,),
mask=True,
dtype=object))
for cand_i, params in enumerate(candidate_params):
_, param_values = params
for name, value in param_values.items():
# An all masked empty array gets created for the key
# `"param_%s" % name` at the first occurence of `name`.
# Setting the value at an index also unmasks that index
param_results["param_%s" % name][cand_i] = value
results.update(param_results)
# Store a list of param dicts at the key 'params'
results['params'] = candidate_params
self.cv_results_ = results
self.best_index_ = best_index
self.n_splits_ = n_splits
self.best_model_ = candidate_params[best_index]
if self.refit:
# build best estimator and fit
best_estimator = _clf_build(self.best_model_[0])
best_estimator.set_params(**best_parameters)
if y is not None:
best_estimator.fit(X, y, **self.fit_params)
else:
best_estimator.fit(X, **self.fit_params)
self.best_estimator_ = best_estimator
return self
def _fit(self, X, y, groups, parameter_iterable):
"""Actual fitting, performing the search over parameters."""
X, y, groups = indexable(X, y, groups)
cv = check_cv(self.cv, y, classifier=True)
n_splits = cv.get_n_splits(X, y, groups)
if self.verbose > 0 and isinstance(parameter_iterable, Sized):
n_candidates = len(parameter_iterable)
LOG.info(
"Fitting %d folds for each of %d candidates, totalling"
" %d fits", n_splits, n_candidates, n_candidates * n_splits)
pre_dispatch = self.pre_dispatch
cv_iter = list(cv.split(X, y, groups))
out = Parallel(n_jobs=self.n_jobs,
verbose=self.verbose,
pre_dispatch=pre_dispatch)(
delayed(_model_fit_and_score)(
estimator,
X,
y,
self.scoring,
train,
test,
self.verbose,
parameters,
fit_params=self.fit_params,
return_train_score=self.return_train_score,
return_n_test_samples=True,
return_times=True,
return_parameters=True,
error_score=self.error_score)
for estimator, parameters in parameter_iterable
for train, test in cv_iter)
# if one choose to see train score, "out" will contain train score info
if self.return_train_score:
(train_scores, test_scores, test_sample_counts, fit_time,
score_time, parameters) = zip(*out)
else:
(test_scores, test_sample_counts, fit_time, score_time,
parameters) = zip(*out)
candidate_params = parameters[::n_splits]
n_candidates = len(candidate_params)
results = dict()
def _store(key_name, array, weights=None, splits=False, rank=False):
"""A small helper to store the scores/times to the cv_results_"""
array = np.array(array,
dtype=np.float64).reshape(n_candidates, n_splits)
if splits:
for split_i in range(n_splits):
results["split%d_%s" %
(split_i, key_name)] = array[:, split_i]
array_means = np.average(array, axis=1, weights=weights)
results['mean_%s' % key_name] = array_means
# Weighted std is not directly available in numpy
array_stds = np.sqrt(
np.average((array - array_means[:, np.newaxis])**2,
axis=1,
weights=weights))
results['std_%s' % key_name] = array_stds
if rank:
results["rank_%s" % key_name] = np.asarray(rankdata(
-array_means, method='min'),
dtype=np.int32)
# Computed the (weighted) mean and std for test scores alone
# NOTE test_sample counts (weights) remain the same for all candidates
test_sample_counts = np.array(test_sample_counts[:n_splits],
dtype=np.int)
_store('test_score',
test_scores,
splits=True,
rank=True,
weights=test_sample_counts if self.iid else None)
if self.return_train_score:
_store('train_score', train_scores, splits=True)
_store('fit_time', fit_time)
_store('score_time', score_time)
best_index = np.flatnonzero(results["rank_test_score"] == 1)[0]
best_parameters = candidate_params[best_index][1]
# Use one MaskedArray and mask all the places where the param is not
# applicable for that candidate. Use defaultdict as each candidate may
# not contain all the params
param_results = defaultdict(
partial(MaskedArray,
np.empty(n_candidates, ),
mask=True,
dtype=object))
for cand_i, params in enumerate(candidate_params):
_, param_values = params
for name, value in param_values.items():
# An all masked empty array gets created for the key
# `"param_%s" % name` at the first occurence of `name`.
# Setting the value at an index also unmasks that index
param_results["param_%s" % name][cand_i] = value
results.update(param_results)
# Store a list of param dicts at the key 'params'
results['params'] = candidate_params
self.cv_results_ = results
self.best_index_ = best_index
self.n_splits_ = n_splits
self.best_model_ = candidate_params[best_index]
if self.refit:
# build best estimator and fit
best_estimator = _clf_build(self.best_model_[0])
best_estimator.set_params(**best_parameters)
if y is not None:
best_estimator.fit(X, y, **self.fit_params)
else:
best_estimator.fit(X, **self.fit_params)
self.best_estimator_ = best_estimator
return self
def fit(self, X, y=None, groups=None, **fit_params):
"""Run fit with all sets of parameters.
Parameters
----------
X : array-like, shape = [n_samples, n_features]
Training vector, where n_samples is the number of samples and
n_features is the number of features.
y : array-like, shape = [n_samples] or [n_samples, n_output], optional
Target relative to X for classification or regression;
None for unsupervised learning.
groups : array-like, with shape (n_samples,), optional
Group labels for the samples used while splitting the dataset into
train/test set.
**fit_params : dict of string -> object
Parameters passed to the ``fit`` method of the estimator
"""
if self.fit_params is not None:
warnings.warn(
'"fit_params" as a constructor argument was '
'deprecated in version 0.19 and will be removed '
'in version 0.21. Pass fit parameters to the '
'"fit" method instead.', DeprecationWarning)
if fit_params:
warnings.warn(
'Ignoring fit_params passed as a constructor '
'argument in favor of keyword arguments to '
'the "fit" method.', RuntimeWarning)
else:
fit_params = self.fit_params
estimator = self.estimator
cv = check_cv(self.cv, y, classifier=is_classifier(estimator))
scorers, self.multimetric_ = _check_multimetric_scoring(
self.estimator, scoring=self.scoring)
if self.multimetric_:
if self.refit is not False and (
not isinstance(self.refit, six.string_types) or
# This will work for both dict / list (tuple)
self.refit not in scorers):
raise ValueError("For multi-metric scoring, the parameter "
"refit must be set to a scorer key "
"to refit an estimator with the best "
"parameter setting on the whole data and "
"make the best_* attributes "
"available for that metric. If this is not "
"needed, refit should be set to False "
"explicitly. %r was passed." % self.refit)
else:
refit_metric = self.refit
else:
refit_metric = 'score'
X, y, groups = indexable(X, y, groups)
n_splits = cv.get_n_splits(X, y, groups)
# Regenerate parameter iterable for each fit
candidate_params = list(self._get_param_iterator())
n_candidates = len(candidate_params)
if self.verbose > 0:
print("Fitting {0} folds for each of {1} candidates, totalling"
" {2} fits".format(n_splits, n_candidates,
n_candidates * n_splits))
base_estimator = clone(self.estimator)
pre_dispatch = self.pre_dispatch
out = Parallel(
n_jobs=self.n_jobs,
verbose=self.verbose,
pre_dispatch=pre_dispatch,
n_tasks=n_candidates * n_splits,
)(delayed(_fit_and_score)(clone(base_estimator),
X,
y,
scorers,
train,
test,
self.verbose,
parameters,
fit_params=fit_params,
return_train_score=self.return_train_score,
return_n_test_samples=True,
return_times=True,
return_parameters=False,
error_score=self.error_score)
for parameters, (
train, test) in product(candidate_params, cv.split(X, y, groups)))
# if one choose to see train score, "out" will contain train score info
if self.return_train_score:
(train_score_dicts, test_score_dicts, test_sample_counts, fit_time,
score_time) = zip(*out)
else:
(test_score_dicts, test_sample_counts, fit_time,
score_time) = zip(*out)
# test_score_dicts and train_score dicts are lists of dictionaries and
# we make them into dict of lists
test_scores = _aggregate_score_dicts(test_score_dicts)
if self.return_train_score:
train_scores = _aggregate_score_dicts(train_score_dicts)
results = dict()
def _store(key_name, array, weights=None, splits=False, rank=False):
"""A small helper to store the scores/times to the cv_results_"""
# When iterated first by splits, then by parameters
# We want `array` to have `n_candidates` rows and `n_splits` cols.
array = np.array(array,
dtype=np.float64).reshape(n_candidates, n_splits)
if splits:
for split_i in range(n_splits):
# Uses closure to alter the results
results["split%d_%s" % (split_i, key_name)] = array[:, split_i]
array_means = np.average(array, axis=1, weights=weights)
results['mean_%s' % key_name] = array_means
# Weighted std is not directly available in numpy
array_stds = np.sqrt(
np.average((array - array_means[:, np.newaxis])**2,
axis=1,
weights=weights))
results['std_%s' % key_name] = array_stds
if rank:
results["rank_%s" % key_name] = np.asarray(rankdata(-array_means,
method='min'),
dtype=np.int32)
_store('fit_time', fit_time)
_store('score_time', score_time)
# Use one MaskedArray and mask all the places where the param is not
# applicable for that candidate. Use defaultdict as each candidate may
# not contain all the params
param_results = defaultdict(
partial(MaskedArray, np.empty(n_candidates, ), mask=True,
dtype=object))
for cand_i, params in enumerate(candidate_params):
for name, value in params.items():
# An all masked empty array gets created for the key
# `"param_%s" % name` at the first occurence of `name`.
# Setting the value at an index also unmasks that index
param_results["param_%s" % name][cand_i] = value
results.update(param_results)
# Store a list of param dicts at the key 'params'
results['params'] = candidate_params
# NOTE test_sample counts (weights) remain the same for all candidates
test_sample_counts = np.array(test_sample_counts[:n_splits], dtype=np.int)
for scorer_name in scorers.keys():
# Computed the (weighted) mean and std for test scores alone
_store('test_%s' % scorer_name,
test_scores[scorer_name],
splits=True,
rank=True,
weights=test_sample_counts if self.iid else None)
if self.return_train_score:
_store('train_%s' % scorer_name,
train_scores[scorer_name],
splits=True)
# For multi-metric evaluation, store the best_index_, best_params_ and
# best_score_ iff refit is one of the scorer names
# In single metric evaluation, refit_metric is "score"
if self.refit or not self.multimetric_:
self.best_index_ = results["rank_test_%s" % refit_metric].argmin()
self.best_params_ = candidate_params[self.best_index_]
self.best_score_ = results["mean_test_%s" %
refit_metric][self.best_index_]
if self.refit:
self.best_estimator_ = clone(base_estimator).set_params(
**self.best_params_)
if y is not None:
self.best_estimator_.fit(X, y, **fit_params)
else:
self.best_estimator_.fit(X, **fit_params)
# Store the only scorer not as a dict for single metric evaluation
self.scorer_ = scorers if self.multimetric_ else scorers['score']
self.cv_results_ = results
self.n_splits_ = n_splits
return self