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sklearn.dummy.DummyClassifier

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

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.

Parameters:

strategy : str

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.
  • “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

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.

Methods

fit(X, y) 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)
fit(X, y)

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.

Returns:

self : object

Returns self.

get_params(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.

predict(X)

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)

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)

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)

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

Parameters:

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

Test samples.

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

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)

Set the parameters of this estimator.

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

Returns:self :
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