imblearn.under_sampling.EditedNearestNeighbours

class imblearn.under_sampling.EditedNearestNeighbours(sampling_strategy='auto', return_indices=False, random_state=None, n_neighbors=3, kind_sel='all', n_jobs=1, ratio=None)[source][source]

Class to perform under-sampling based on the edited nearest neighbour method.

Read more in the User Guide.

Parameters:
sampling_strategy : str, list or callable

Sampling information to sample the data set.

  • When str, specify the class targeted by the resampling. Note the the number of samples will not be equal in each. Possible choices are:

    'majority': resample only the majority class;

    'not minority': resample all classes but the minority class;

    'not majority': resample all classes but the majority class;

    'all': resample all classes;

    'auto': equivalent to 'not minority'.

  • When list, the list contains the classes targeted by the resampling.

  • When callable, function taking y and returns a dict. The keys correspond to the targeted classes. The values correspond to the desired number of samples for each class.

return_indices : bool, optional (default=False)

Whether or not to return the indices of the samples randomly selected.

Deprecated since version 0.4: return_indices is deprecated. Use the attribute sample_indices_ instead.

random_state : int, RandomState instance or None, optional (default=None)

Control the randomization of the algorithm.

  • If int, random_state is the seed used by the random number generator;
  • If RandomState instance, random_state is the random number generator;
  • If None, the random number generator is the RandomState instance used by np.random.

Deprecated since version 0.4: random_state is deprecated in 0.4 and will be removed in 0.6.

n_neighbors : int or object, optional (default=3)

If int, size of the neighbourhood to consider to compute the nearest neighbors. If object, an estimator that inherits from sklearn.neighbors.base.KNeighborsMixin that will be used to find the nearest-neighbors.

kind_sel : str, optional (default=’all’)

Strategy to use in order to exclude samples.

  • If 'all', all neighbours will have to agree with the samples of interest to not be excluded.
  • If 'mode', the majority vote of the neighbours will be used in order to exclude a sample.
n_jobs : int, optional (default=1)

The number of threads to open if possible.

ratio : str, dict, or callable

Deprecated since version 0.4: Use the parameter sampling_strategy instead. It will be removed in 0.6.

Notes

The method is based on [1].

Supports multi-class resampling. A one-vs.-rest scheme is used when sampling a class as proposed in [1].

References

[1](1, 2, 3) D. Wilson, Asymptotic” Properties of Nearest Neighbor Rules Using Edited Data,” In IEEE Transactions on Systems, Man, and Cybernetrics, vol. 2 (3), pp. 408-421, 1972.

Examples

>>> from collections import Counter
>>> from sklearn.datasets import make_classification
>>> from imblearn.under_sampling import EditedNearestNeighbours # doctest: +NORMALIZE_WHITESPACE
>>> X, y = make_classification(n_classes=2, class_sep=2,
... weights=[0.1, 0.9], n_informative=3, n_redundant=1, flip_y=0,
... n_features=20, n_clusters_per_class=1, n_samples=1000, random_state=10)
>>> print('Original dataset shape %s' % Counter(y))
Original dataset shape Counter({1: 900, 0: 100})
>>> enn = EditedNearestNeighbours()
>>> X_res, y_res = enn.fit_resample(X, y)
>>> print('Resampled dataset shape %s' % Counter(y_res))
Resampled dataset shape Counter({1: 887, 0: 100})
Attributes:
sample_indices_ : ndarray, shape (n_new_samples)

Indices of the samples selected.

New in version 0.4: sample_indices_ used instead of return_indices=True.

__init__(sampling_strategy='auto', return_indices=False, random_state=None, n_neighbors=3, kind_sel='all', n_jobs=1, ratio=None)[source][source]

Initialize self. See help(type(self)) for accurate signature.

fit(X, y)[source]

Check inputs and statistics of the sampler.

You should use fit_resample in all cases.

Parameters:
X : {array-like, sparse matrix}, shape (n_samples, n_features)

Data array.

y : array-like, shape (n_samples,)

Target array.

Returns:
self : object

Return the instance itself.

fit_resample(X, y)[source]

Resample the dataset.

Parameters:
X : {array-like, sparse matrix}, shape (n_samples, n_features)

Matrix containing the data which have to be sampled.

y : array-like, shape (n_samples,)

Corresponding label for each sample in X.

Returns:
X_resampled : {array-like, sparse matrix}, shape (n_samples_new, n_features)

The array containing the resampled data.

y_resampled : array-like, shape (n_samples_new,)

The corresponding label of X_resampled.

fit_sample(X, y)[source]

Resample the dataset.

Parameters:
X : {array-like, sparse matrix}, shape (n_samples, n_features)

Matrix containing the data which have to be sampled.

y : array-like, shape (n_samples,)

Corresponding label for each sample in X.

Returns:
X_resampled : {array-like, sparse matrix}, shape (n_samples_new, n_features)

The array containing the resampled data.

y_resampled : array-like, shape (n_samples_new,)

The corresponding label of X_resampled.

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.

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

Examples using imblearn.under_sampling.EditedNearestNeighbours