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/ pipeline.py
"""
The :mod:`sklearn.pipeline` module implements utilities to build a composite
estimator, as a chain of transforms and estimators.
"""
# Author: Edouard Duchesnay
# Gael Varoquaux
# Virgile Fritsch
# Alexandre Gramfort
# Lars Buitinck
# License: BSD
from collections import defaultdict
from itertools import islice
import warnings
import numpy as np
from scipy import sparse
from joblib import Parallel, delayed
from .base import clone, TransformerMixin
from .utils.metaestimators import if_delegate_has_method
from .utils import Bunch, _print_elapsed_time
from .utils.validation import check_memory
from .utils.metaestimators import _BaseComposition
__all__ = ['Pipeline', 'FeatureUnion', 'make_pipeline', 'make_union']
class Pipeline(_BaseComposition):
"""
Pipeline of transforms with a final estimator.
Sequentially apply a list of transforms and a final estimator.
Intermediate steps of the pipeline must be 'transforms', that is, they
must implement fit and transform methods.
The final estimator only needs to implement fit.
The transformers in the pipeline can be cached using ``memory`` argument.
The purpose of the pipeline is to assemble several steps that can be
cross-validated together while setting different parameters.
For this, it enables setting parameters of the various steps using their
names and the parameter name separated by a '__', as in the example below.
A step's estimator may be replaced entirely by setting the parameter
with its name to another estimator, or a transformer removed by setting
it to 'passthrough' or ``None``.
Read more in the :ref:`User Guide <pipeline>`.
Parameters
----------
steps : list
List of (name, transform) tuples (implementing fit/transform) that are
chained, in the order in which they are chained, with the last object
an estimator.
memory : None, str or object with the joblib.Memory interface, optional
Used to cache the fitted transformers of the pipeline. By default,
no caching is performed. If a string is given, it is the path to
the caching directory. Enabling caching triggers a clone of
the transformers before fitting. Therefore, the transformer
instance given to the pipeline cannot be inspected
directly. Use the attribute ``named_steps`` or ``steps`` to
inspect estimators within the pipeline. Caching the
transformers is advantageous when fitting is time consuming.
verbose : bool, default=False
If True, the time elapsed while fitting each step will be printed as it
is completed.
Attributes
----------
named_steps : bunch object, a dictionary with attribute access
Read-only attribute to access any step parameter by user given name.
Keys are step names and values are steps parameters.
See Also
--------
sklearn.pipeline.make_pipeline : Convenience function for simplified
pipeline construction.
Examples
--------
>>> from sklearn import svm
>>> from sklearn.datasets import make_classification
>>> from sklearn.feature_selection import SelectKBest
>>> from sklearn.feature_selection import f_regression
>>> from sklearn.pipeline import Pipeline
>>> # generate some data to play with
>>> X, y = make_classification(
... n_informative=5, n_redundant=0, random_state=42)
>>> # ANOVA SVM-C
>>> anova_filter = SelectKBest(f_regression, k=5)
>>> clf = svm.SVC(kernel='linear')
>>> anova_svm = Pipeline([('anova', anova_filter), ('svc', clf)])
>>> # You can set the parameters using the names issued
>>> # For instance, fit using a k of 10 in the SelectKBest
>>> # and a parameter 'C' of the svm
>>> anova_svm.set_params(anova__k=10, svc__C=.1).fit(X, y)
Pipeline(steps=[('anova', SelectKBest(...)), ('svc', SVC(...))])
>>> prediction = anova_svm.predict(X)
>>> anova_svm.score(X, y)
0.83
>>> # getting the selected features chosen by anova_filter
>>> anova_svm['anova'].get_support()
array([False, False, True, True, False, False, True, True, False,
True, False, True, True, False, True, False, True, True,
False, False])
>>> # Another way to get selected features chosen by anova_filter
>>> anova_svm.named_steps.anova.get_support()
array([False, False, True, True, False, False, True, True, False,
True, False, True, True, False, True, False, True, True,
False, False])
>>> # Indexing can also be used to extract a sub-pipeline.
>>> sub_pipeline = anova_svm[:1]
>>> sub_pipeline
Pipeline(steps=[('anova', SelectKBest(...))])
>>> coef = anova_svm[-1].coef_
>>> anova_svm['svc'] is anova_svm[-1]
True
>>> coef.shape
(1, 10)
>>> sub_pipeline.inverse_transform(coef).shape
(1, 20)
"""
# BaseEstimator interface
_required_parameters = ['steps']
def __init__(self, steps, memory=None, verbose=False):
self.steps = steps
self.memory = memory
self.verbose = verbose
self._validate_steps()
def get_params(self, deep=True):
"""Get parameters for this estimator.
Parameters
----------
deep : boolean, optional
If True, will return the parameters for this estimator and
contained subobjects that are estimators.
Returns
-------
params : mapping of string to any
Parameter names mapped to their values.
"""
return self._get_params('steps', deep=deep)
def set_params(self, **kwargs):
"""Set the parameters of this estimator.
Valid parameter keys can be listed with ``get_params()``.
Returns
-------
self
"""
self._set_params('steps', **kwargs)
return self
def _validate_steps(self):
names, estimators = zip(*self.steps)
# validate names
self._validate_names(names)
# validate estimators
transformers = estimators[:-1]
estimator = estimators[-1]
for t in transformers:
if t is None or t == 'passthrough':
continue
if (not (hasattr(t, "fit") or hasattr(t, "fit_transform")) or not
hasattr(t, "transform")):
raise TypeError("All intermediate steps should be "
"transformers and implement fit and transform "
"or be the string 'passthrough' "
"'%s' (type %s) doesn't" % (t, type(t)))
# We allow last estimator to be None as an identity transformation
if (estimator is not None and estimator != 'passthrough'
and not hasattr(estimator, "fit")):
raise TypeError(
"Last step of Pipeline should implement fit "
"or be the string 'passthrough'. "
"'%s' (type %s) doesn't" % (estimator, type(estimator)))
def _iter(self, with_final=True, filter_passthrough=True):
"""
Generate (idx, (name, trans)) tuples from self.steps
When filter_passthrough is True, 'passthrough' and None transformers
are filtered out.
"""
stop = len(self.steps)
if not with_final:
stop -= 1
for idx, (name, trans) in enumerate(islice(self.steps, 0, stop)):
if not filter_passthrough:
yield idx, name, trans
elif trans is not None and trans != 'passthrough':
yield idx, name, trans
def __len__(self):
"""
Returns the length of the Pipeline
"""
return len(self.steps)
def __getitem__(self, ind):
"""Returns a sub-pipeline or a single esimtator in the pipeline
Indexing with an integer will return an estimator; using a slice
returns another Pipeline instance which copies a slice of this
Pipeline. This copy is shallow: modifying (or fitting) estimators in
the sub-pipeline will affect the larger pipeline and vice-versa.
However, replacing a value in `step` will not affect a copy.
"""
if isinstance(ind, slice):
if ind.step not in (1, None):
raise ValueError('Pipeline slicing only supports a step of 1')
return self.__class__(self.steps[ind])
try:
name, est = self.steps[ind]
except TypeError:
# Not an int, try get step by name
return self.named_steps[ind]
return est
@property
def _estimator_type(self):
return self.steps[-1][1]._estimator_type
@property
def named_steps(self):
# Use Bunch object to improve autocomplete
return Bunch(**dict(self.steps))
@property
def _final_estimator(self):
estimator = self.steps[-1][1]
return 'passthrough' if estimator is None else estimator
def _log_message(self, step_idx):
if not self.verbose:
return None
name, step = self.steps[step_idx]
return '(step %d of %d) Processing %s' % (step_idx + 1,
len(self.steps),
name)
# Estimator interface
def _fit(self, X, y=None, **fit_params):
# shallow copy of steps - this should really be steps_
self.steps = list(self.steps)
self._validate_steps()
# Setup the memory
memory = check_memory(self.memory)
fit_transform_one_cached = memory.cache(_fit_transform_one)
fit_params_steps = {name: {} for name, step in self.steps
if step is not None}
for pname, pval in fit_params.items():
if '__' not in pname:
raise ValueError(
"Pipeline.fit does not accept the {} parameter. "
"You can pass parameters to specific steps of your "
"pipeline using the stepname__parameter format, e.g. "
"`Pipeline.fit(X, y, logisticregression__sample_weight"
"=sample_weight)`.".format(pname))
step, param = pname.split('__', 1)
fit_params_steps[step][param] = pval
for (step_idx,
name,
transformer) in self._iter(with_final=False,
filter_passthrough=False):
if (transformer is None or transformer == 'passthrough'):
with _print_elapsed_time('Pipeline',
self._log_message(step_idx)):
continue
if hasattr(memory, 'location'):
# joblib >= 0.12
if memory.location is None:
# we do not clone when caching is disabled to
# preserve backward compatibility
cloned_transformer = transformer
else:
cloned_transformer = clone(transformer)
elif hasattr(memory, 'cachedir'):
# joblib < 0.11
if memory.cachedir is None:
# we do not clone when caching is disabled to
# preserve backward compatibility
cloned_transformer = transformer
else:
cloned_transformer = clone(transformer)
else:
cloned_transformer = clone(transformer)
# Fit or load from cache the current transfomer
X, fitted_transformer = fit_transform_one_cached(
cloned_transformer, X, y, None,
message_clsname='Pipeline',
message=self._log_message(step_idx),
**fit_params_steps[name])
# Replace the transformer of the step with the fitted
# transformer. This is necessary when loading the transformer
# from the cache.
self.steps[step_idx] = (name, fitted_transformer)
if self._final_estimator == 'passthrough':
return X, {}
return X, fit_params_steps[self.steps[-1][0]]
def fit(self, X, y=None, **fit_params):
"""Fit the model
Fit all the transforms one after the other and transform the
data, then fit the transformed data using the final estimator.
Parameters
----------
X : iterable
Training data. Must fulfill input requirements of first step of the
pipeline.
y : iterable, default=None
Training targets. Must fulfill label requirements for all steps of
the pipeline.
**fit_params : dict of string -> object
Parameters passed to the ``fit`` method of each step, where
each parameter name is prefixed such that parameter ``p`` for step
``s`` has key ``s__p``.
Returns
-------
self : Pipeline
This estimator
"""
Xt, fit_params = self._fit(X, y, **fit_params)
with _print_elapsed_time('Pipeline',
self._log_message(len(self.steps) - 1)):
if self._final_estimator != 'passthrough':
self._final_estimator.fit(Xt, y, **fit_params)
return self
def fit_transform(self, X, y=None, **fit_params):
"""Fit the model and transform with the final estimator
Fits all the transforms one after the other and transforms the
data, then uses fit_transform on transformed data with the final
estimator.
Parameters
----------
X : iterable
Training data. Must fulfill input requirements of first step of the
pipeline.
y : iterable, default=None
Training targets. Must fulfill label requirements for all steps of
the pipeline.
**fit_params : dict of string -> object
Parameters passed to the ``fit`` method of each step, where
each parameter name is prefixed such that parameter ``p`` for step
``s`` has key ``s__p``.
Returns
-------
Xt : array-like of shape (n_samples, n_transformed_features)
Transformed samples
"""
last_step = self._final_estimator
Xt, fit_params = self._fit(X, y, **fit_params)
with _print_elapsed_time('Pipeline',
self._log_message(len(self.steps) - 1)):
if last_step == 'passthrough':
return Xt
if hasattr(last_step, 'fit_transform'):
return last_step.fit_transform(Xt, y, **fit_params)
else:
return last_step.fit(Xt, y, **fit_params).transform(Xt)
@if_delegate_has_method(delegate='_final_estimator')
def predict(self, X, **predict_params):
"""Apply transforms to the data, and predict with the final estimator
Parameters
----------
X : iterable
Data to predict on. Must fulfill input requirements of first step
of the pipeline.
**predict_params : dict of string -> object
Parameters to the ``predict`` called at the end of all
transformations in the pipeline. Note that while this may be
used to return uncertainties from some models with return_std
or return_cov, uncertainties that are generated by the
transformations in the pipeline are not propagated to the
final estimator.
Returns
-------
y_pred : array-like
"""
Xt = X
for _, name, transform in self._iter(with_final=False):
Xt = transform.transform(Xt)
return self.steps[-1][-1].predict(Xt, **predict_params)
@if_delegate_has_method(delegate='_final_estimator')
def fit_predict(self, X, y=None, **fit_params):
"""Applies fit_predict of last step in pipeline after transforms.
Applies fit_transforms of a pipeline to the data, followed by the
fit_predict method of the final estimator in the pipeline. Valid
only if the final estimator implements fit_predict.
Parameters
----------
X : iterable
Training data. Must fulfill input requirements of first step of
the pipeline.
y : iterable, default=None
Training targets. Must fulfill label requirements for all steps
of the pipeline.
**fit_params : dict of string -> object
Parameters passed to the ``fit`` method of each step, where
each parameter name is prefixed such that parameter ``p`` for step
``s`` has key ``s__p``.
Returns
-------
y_pred : array-like
"""
Xt, fit_params = self._fit(X, y, **fit_params)
with _print_elapsed_time('Pipeline',
self._log_message(len(self.steps) - 1)):
y_pred = self.steps[-1][-1].fit_predict(Xt, y, **fit_params)
return y_pred
@if_delegate_has_method(delegate='_final_estimator')
def predict_proba(self, X):
"""Apply transforms, and predict_proba of the final estimator
Parameters
----------
X : iterable
Data to predict on. Must fulfill input requirements of first step
of the pipeline.
Returns
-------
y_proba : array-like of shape (n_samples, n_classes)
"""
Xt = X
for _, name, transform in self._iter(with_final=False):
Xt = transform.transform(Xt)
return self.steps[-1][-1].predict_proba(Xt)
@if_delegate_has_method(delegate='_final_estimator')
def decision_function(self, X):
"""Apply transforms, and decision_function of the final estimator
Parameters
----------
X : iterable
Data to predict on. Must fulfill input requirements of first step
of the pipeline.
Returns
-------
y_score : array-like of shape (n_samples, n_classes)
"""
Xt = X
for _, name, transform in self._iter(with_final=False):
Xt = transform.transform(Xt)
return self.steps[-1][-1].decision_function(Xt)
@if_delegate_has_method(delegate='_final_estimator')
def score_samples(self, X):
"""Apply transforms, and score_samples of the final estimator.
Parameters
----------
X : iterable
Data to predict on. Must fulfill input requirements of first step
of the pipeline.
Returns
-------
y_score : ndarray, shape (n_samples,)
"""
Xt = X
for _, _, transformer in self._iter(with_final=False):
Xt = transformer.transform(Xt)
return self.steps[-1][-1].score_samples(Xt)
@if_delegate_has_method(delegate='_final_estimator')
def predict_log_proba(self, X):
"""Apply transforms, and predict_log_proba of the final estimator
Parameters
----------
X : iterable
Data to predict on. Must fulfill input requirements of first step
of the pipeline.
Returns
-------
y_score : array-like of shape (n_samples, n_classes)
"""
Xt = X
for _, name, transform in self._iter(with_final=False):
Xt = transform.transform(Xt)
return self.steps[-1][-1].predict_log_proba(Xt)
@property
def transform(self):
"""Apply transforms, and transform with the final estimator
This also works where final estimator is ``None``: all prior
transformations are applied.
Parameters
----------
X : iterable
Data to transform. Must fulfill input requirements of first step
of the pipeline.
Returns
-------
Xt : array-like of shape (n_samples, n_transformed_features)
"""
# _final_estimator is None or has transform, otherwise attribute error
# XXX: Handling the None case means we can't use if_delegate_has_method
if self._final_estimator != 'passthrough':
self._final_estimator.transform
return self._transform
def _transform(self, X):
Xt = X
for _, _, transform in self._iter():
Xt = transform.transform(Xt)
return Xt
@property
def inverse_transform(self):
"""Apply inverse transformations in reverse order
All estimators in the pipeline must support ``inverse_transform``.
Parameters
----------
Xt : array-like of shape (n_samples, n_transformed_features)
Data samples, where ``n_samples`` is the number of samples and
``n_features`` is the number of features. Must fulfill
input requirements of last step of pipeline's
``inverse_transform`` method.
Returns
-------
Xt : array-like of shape (n_samples, n_features)
"""
# raise AttributeError if necessary for hasattr behaviour
# XXX: Handling the None case means we can't use if_delegate_has_method
for _, _, transform in self._iter():
transform.inverse_transform
return self._inverse_transform
def _inverse_transform(self, X):
Xt = X
reverse_iter = reversed(list(self._iter()))
for _, _, transform in reverse_iter:
Xt = transform.inverse_transform(Xt)
return Xt
@if_delegate_has_method(delegate='_final_estimator')
def score(self, X, y=None, sample_weight=None):
"""Apply transforms, and score with the final estimator
Parameters
----------
X : iterable
Data to predict on. Must fulfill input requirements of first step
of the pipeline.
y : iterable, default=None
Targets used for scoring. Must fulfill label requirements for all
steps of the pipeline.
sample_weight : array-like, default=None
If not None, this argument is passed as ``sample_weight`` keyword
argument to the ``score`` method of the final estimator.
Returns
-------
score : float
"""
Xt = X
for _, name, transform in self._iter(with_final=False):
Xt = transform.transform(Xt)
score_params = {}
if sample_weight is not None:
score_params['sample_weight'] = sample_weight
return self.steps[-1][-1].score(Xt, y, **score_params)
@property
def classes_(self):
return self.steps[-1][-1].classes_
@property
def _pairwise(self):
# check if first estimator expects pairwise input
return getattr(self.steps[0][1], '_pairwise', False)
def _name_estimators(estimators):
"""Generate names for estimators."""
names = [
estimator
if isinstance(estimator, str) else type(estimator).__name__.lower()
for estimator in estimators
]
namecount = defaultdict(int)
for est, name in zip(estimators, names):
namecount[name] += 1
for k, v in list(namecount.items()):
if v == 1:
del namecount[k]
for i in reversed(range(len(estimators))):
name = names[i]
if name in namecount:
names[i] += "-%d" % namecount[name]
namecount[name] -= 1
return list(zip(names, estimators))
def make_pipeline(*steps, **kwargs):
"""Construct a Pipeline from the given estimators.
This is a shorthand for the Pipeline constructor; it does not require, and
does not permit, naming the estimators. Instead, their names will be set
to the lowercase of their types automatically.
Parameters
----------
*steps : list of estimators.
memory : None, str or object with the joblib.Memory interface, optional
Used to cache the fitted transformers of the pipeline. By default,
no caching is performed. If a string is given, it is the path to
the caching directory. Enabling caching triggers a clone of
the transformers before fitting. Therefore, the transformer
instance given to the pipeline cannot be inspected
directly. Use the attribute ``named_steps`` or ``steps`` to
inspect estimators within the pipeline. Caching the
transformers is advantageous when fitting is time consuming.
verbose : boolean, default=False
If True, the time elapsed while fitting each step will be printed as it
is completed.
See Also
--------
sklearn.pipeline.Pipeline : Class for creating a pipeline of
transforms with a final estimator.
Examples
--------
>>> from sklearn.naive_bayes import GaussianNB
>>> from sklearn.preprocessing import StandardScaler
>>> make_pipeline(StandardScaler(), GaussianNB(priors=None))
Pipeline(steps=[('standardscaler', StandardScaler()),
('gaussiannb', GaussianNB())])
Returns
-------
p : Pipeline
"""
memory = kwargs.pop('memory', None)
verbose = kwargs.pop('verbose', False)
if kwargs:
raise TypeError('Unknown keyword arguments: "{}"'
.format(list(kwargs.keys())[0]))
return Pipeline(_name_estimators(steps), memory=memory, verbose=verbose)
def _transform_one(transformer, X, y, weight, **fit_params):
res = transformer.transform(X)
# if we have a weight for this transformer, multiply output
if weight is None:
return res
return res * weight
def _fit_transform_one(transformer,
X,
y,
weight,
message_clsname='',
message=None,
**fit_params):
"""
Fits ``transformer`` to ``X`` and ``y``. The transformed result is returned
with the fitted transformer. If ``weight`` is not ``None``, the result will
be multiplied by ``weight``.
"""
with _print_elapsed_time(message_clsname, message):
if hasattr(transformer, 'fit_transform'):
res = transformer.fit_transform(X, y, **fit_params)
else:
res = transformer.fit(X, y, **fit_params).transform(X)
if weight is None:
return res, transformer
return res * weight, transformer
def _fit_one(transformer,
X,
y,
weight,
message_clsname='',
message=None,
**fit_params):
"""
Fits ``transformer`` to ``X`` and ``y``.
"""
with _print_elapsed_time(message_clsname, message):
return transformer.fit(X, y, **fit_params)
class FeatureUnion(TransformerMixin, _BaseComposition):
"""Concatenates results of multiple transformer objects.
This estimator applies a list of transformer objects in parallel to the
input data, then concatenates the results. This is useful to combine
several feature extraction mechanisms into a single transformer.
Parameters of the transformers may be set using its name and the parameter
name separated by a '__'. A transformer may be replaced entirely by
setting the parameter with its name to another transformer,
or removed by setting to 'drop'.
Read more in the :ref:`User Guide <feature_union>`.
.. versionadded:: 0.13
Parameters
----------
transformer_list : list of (string, transformer) tuples
List of transformer objects to be applied to the data. The first
half of each tuple is the name of the transformer.
.. versionchanged:: 0.22
Deprecated `None` as a transformer in favor of 'drop'.
n_jobs : int or None, optional (default=None)
Number of jobs to run in parallel.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
transformer_weights : dict, optional
Multiplicative weights for features per transformer.
Keys are transformer names, values the weights.
verbose : boolean, optional(default=False)
If True, the time elapsed while fitting each transformer will be
printed as it is completed.
See Also
--------
sklearn.pipeline.make_union : Convenience function for simplified
feature union construction.
Examples
--------
>>> from sklearn.pipeline import FeatureUnion
>>> from sklearn.decomposition import PCA, TruncatedSVD
>>> union = FeatureUnion([("pca", PCA(n_components=1)),
... ("svd", TruncatedSVD(n_components=2))])
>>> X = [[0., 1., 3], [2., 2., 5]]
>>> union.fit_transform(X)
array([[ 1.5 , 3.0..., 0.8...],
[-1.5 , 5.7..., -0.4...]])
"""
_required_parameters = ["transformer_list"]
def __init__(self, transformer_list, n_jobs=None,
transformer_weights=None, verbose=False):
self.transformer_list = transformer_list
self.n_jobs = n_jobs
self.transformer_weights = transformer_weights
self.verbose = verbose
self._validate_transformers()
def get_params(self, deep=True):
"""Get parameters for this estimator.
Parameters
----------
deep : boolean, optional
If True, will return the parameters for this estimator and
contained subobjects that are estimators.
Returns
-------
params : mapping of string to any
Parameter names mapped to their values.
"""
return self._get_params('transformer_list', deep=deep)
def set_params(self, **kwargs):
"""Set the parameters of this estimator.
Valid parameter keys can be listed with ``get_params()``.
Returns
-------
self
"""
self._set_params('transformer_list', **kwargs)
return self
def _validate_transformers(self):
names, transformers = zip(*self.transformer_list)
# validate names
self._validate_names(names)
# validate estimators
for t in transformers:
# TODO: Remove in 0.24 when None is removed
if t is None:
warnings.warn("Using None as a transformer is deprecated "
"in version 0.22 and will be removed in "
"version 0.24. Please use 'drop' instead.",
FutureWarning)
continue
if t == 'drop':
continue
if (not (hasattr(t, "fit") or hasattr(t, "fit_transform")) or not
hasattr(t, "transform")):
raise TypeError("All estimators should implement fit and "
"transform. '%s' (type %s) doesn't" %
(t, type(t)))
def _iter(self):
"""
Generate (name, trans, weight) tuples excluding None and
'drop' transformers.
"""
get_weight = (self.transformer_weights or {}).get
return ((name, trans, get_weight(name))
for name, trans in self.transformer_list
if trans is not None and trans != 'drop')
def get_feature_names(self):
"""Get feature names from all transformers.
Returns
-------
feature_names : list of strings
Names of the features produced by transform.
"""
feature_names = []
for name, trans, weight in self._iter():
if not hasattr(trans, 'get_feature_names'):
raise AttributeError("Transformer %s (type %s) does not "
"provide get_feature_names."
% (str(name), type(trans).__name__))
feature_names.extend([name + "__" + f for f in
trans.get_feature_names()])
return feature_names
def fit(self, X, y=None, **fit_params):
"""Fit all transformers using X.
Parameters
----------
X : iterable or array-like, depending on transformers
Input data, used to fit transformers.
y : array-like, shape (n_samples, ...), optional
Targets for supervised learning.
Returns
-------
self : FeatureUnion
This estimator
"""
transformers = self._parallel_func(X, y, fit_params, _fit_one)
if not transformers:
# All transformers are None
return self
self._update_transformer_list(transformers)
return self
def fit_transform(self, X, y=None, **fit_params):
"""Fit all transformers, transform the data and concatenate results.
Parameters
----------
X : iterable or array-like, depending on transformers
Input data to be transformed.
y : array-like, shape (n_samples, ...), optional
Targets for supervised learning.
Returns
-------
X_t : array-like or sparse matrix, shape (n_samples, sum_n_components)
hstack of results of transformers. sum_n_components is the
sum of n_components (output dimension) over transformers.
"""
results = self._parallel_func(X, y, fit_params, _fit_transform_one)
if not results:
# All transformers are None
return np.zeros((X.shape[0], 0))
Xs, transformers = zip(*results)
self._update_transformer_list(transformers)
if any(sparse.issparse(f) for f in Xs):
Xs = sparse.hstack(Xs).tocsr()
else:
Xs = np.hstack(Xs)
return Xs
def _log_message(self, name, idx, total):
if not self.verbose:
return None
return '(step %d of %d) Processing %s' % (idx, total, name)
def _parallel_func(self, X, y, fit_params, func):
"""Runs func in parallel on X and y"""
self.transformer_list = list(self.transformer_list)
self._validate_transformers()
transformers = list(self._iter())
return Parallel(n_jobs=self.n_jobs)(delayed(func)(
transformer, X, y, weight,
message_clsname='FeatureUnion',
message=self._log_message(name, idx, len(transformers)),
**fit_params) for idx, (name, transformer,
weight) in enumerate(transformers, 1))
def transform(self, X):
"""Transform X separately by each transformer, concatenate results.
Parameters
----------
X : iterable or array-like, depending on transformers
Input data to be transformed.
Returns
-------
X_t : array-like or sparse matrix, shape (n_samples, sum_n_components)
hstack of results of transformers. sum_n_components is the
sum of n_components (output dimension) over transformers.
"""
Xs = Parallel(n_jobs=self.n_jobs)(
delayed(_transform_one)(trans, X, None, weight)
for name, trans, weight in self._iter())
if not Xs:
# All transformers are None
return np.zeros((X.shape[0], 0))
if any(sparse.issparse(f) for f in Xs):
Xs = sparse.hstack(Xs).tocsr()
else:
Xs = np.hstack(Xs)
return Xs
def _update_transformer_list(self, transformers):
transformers = iter(transformers)
self.transformer_list[:] = [(name, old if old is None or old == 'drop'
else next(transformers))
for name, old in self.transformer_list]
def make_union(*transformers, **kwargs):
"""
Construct a FeatureUnion from the given transformers.
This is a shorthand for the FeatureUnion constructor; it does not require,
and does not permit, naming the transformers. Instead, they will be given
names automatically based on their types. It also does not allow weighting.
Parameters
----------
*transformers : list of estimators
n_jobs : int or None, optional (default=None)
Number of jobs to run in parallel.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
verbose : boolean, optional(default=False)
If True, the time elapsed while fitting each transformer will be
printed as it is completed.
Returns
-------
f : FeatureUnion
See Also
--------
sklearn.pipeline.FeatureUnion : Class for concatenating the results
of multiple transformer objects.
Examples
--------
>>> from sklearn.decomposition import PCA, TruncatedSVD
>>> from sklearn.pipeline import make_union
>>> make_union(PCA(), TruncatedSVD())
FeatureUnion(transformer_list=[('pca', PCA()),
('truncatedsvd', TruncatedSVD())])
"""
n_jobs = kwargs.pop('n_jobs', None)
verbose = kwargs.pop('verbose', False)
if kwargs:
# We do not currently support `transformer_weights` as we may want to
# change its type spec in make_union
raise TypeError('Unknown keyword arguments: "{}"'
.format(list(kwargs.keys())[0]))
return FeatureUnion(
_name_estimators(transformers), n_jobs=n_jobs, verbose=verbose)