dummy.DummyClassifier()

class sklearn.dummy.DummyClassifier(strategy='stratified', random_state=None, constant=None) [source]

DummyClassifier is a classifier that makes predictions using simple rules.

This classifier is useful as a simple baseline to compare with other (real) classifiers. Do not use it for real problems.

Read more in the User Guide.

Parameters:

strategy : str, default=?stratified?

Strategy to use to generate predictions.

  • ?stratified?: generates predictions by respecting the training set?s class distribution.
  • ?most_frequent?: always predicts the most frequent label in the training set.
  • ?prior?: always predicts the class that maximizes the class prior (like ?most_frequent?) and predict_proba returns the class prior.
  • ?uniform?: generates predictions uniformly at random.
  • ?constant?: always predicts a constant label that is provided by the user. This is useful for metrics that evaluate a non-majority class

    New in version 0.17: Dummy Classifier now supports prior fitting strategy using parameter prior.

random_state : int seed, RandomState instance, or None (default)

The seed of the pseudo random number generator to use.

constant : int or str or array of shape = [n_outputs]

The explicit constant as predicted by the ?constant? strategy. This parameter is useful only for the ?constant? strategy.

Attributes:

classes_ : array or list of array of shape = [n_classes]

Class labels for each output.

n_classes_ : array or list of array of shape = [n_classes]

Number of label for each output.

class_prior_ : array or list of array of shape = [n_classes]

Probability of each class for each output.

n_outputs_ : int,

Number of outputs.

outputs_2d_ : bool,

True if the output at fit is 2d, else false.

sparse_output_ : bool,

True if the array returned from predict is to be in sparse CSC format. Is automatically set to True if the input y is passed in sparse format.

Methods

fit(X, y[, sample_weight]) Fit the random classifier.
get_params([deep]) Get parameters for this estimator.
predict(X) Perform classification on test vectors X.
predict_log_proba(X) Return log probability estimates for the test vectors X.
predict_proba(X) Return probability estimates for the test vectors X.
score(X, y[, sample_weight]) Returns the mean accuracy on the given test data and labels.
set_params(\*\*params) Set the parameters of this estimator.
__init__(strategy='stratified', random_state=None, constant=None) [source]
fit(X, y, sample_weight=None) [source]

Fit the random classifier.

Parameters:

X : {array-like, sparse matrix}, shape = [n_samples, n_features]

Training vectors, 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_outputs]

Target values.

sample_weight : array-like of shape = [n_samples], optional

Sample weights.

Returns:

self : object

Returns self.

get_params(deep=True) [source]

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.

predict(X) [source]

Perform classification on test vectors X.

Parameters:

X : {array-like, sparse matrix}, shape = [n_samples, n_features]

Input vectors, where n_samples is the number of samples and n_features is the number of features.

Returns:

y : array, shape = [n_samples] or [n_samples, n_outputs]

Predicted target values for X.

predict_log_proba(X) [source]

Return log probability estimates for the test vectors X.

Parameters:

X : {array-like, sparse matrix}, shape = [n_samples, n_features]

Input vectors, where n_samples is the number of samples and n_features is the number of features.

Returns:

P : array-like or list of array-like of shape = [n_samples, n_classes]

Returns the log probability of the sample for each class in the model, where classes are ordered arithmetically for each output.

predict_proba(X) [source]

Return probability estimates for the test vectors X.

Parameters:

X : {array-like, sparse matrix}, shape = [n_samples, n_features]

Input vectors, where n_samples is the number of samples and n_features is the number of features.

Returns:

P : array-like or list of array-lke of shape = [n_samples, n_classes]

Returns the probability of the sample for each class in the model, where classes are ordered arithmetically, for each output.

score(X, y, sample_weight=None) [source]

Returns the mean accuracy on the given test data and labels.

In multi-label classification, this is the subset accuracy which is a harsh metric since you require for each sample that each label set be correctly predicted.

Parameters:

X : array-like, shape = (n_samples, n_features)

Test samples.

y : array-like, shape = (n_samples) or (n_samples, n_outputs)

True labels for X.

sample_weight : array-like, shape = [n_samples], optional

Sample weights.

Returns:

score : float

Mean accuracy of self.predict(X) wrt. y.

set_params(**params) [source]

Set the parameters of this estimator.

The method works on simple estimators as well as on nested objects (such as pipelines). The latter have parameters of the form <component>__<parameter> so that it?s possible to update each component of a nested object.

Returns: self :
doc_scikit_learn
2017-01-15 04:21:34
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