pyriemann.classification.KNearestNeighbor

class pyriemann.classification.KNearestNeighbor(n_neighbors=5, metric='riemann', n_jobs=1)

Classification by k-nearest neighbors.

Classification by k-nearest neighbors (k-NN). For each point of the test set, the pairwise distance to each element of the training set is estimated. The class is affected according to the majority class of the k-nearest neighbors.

Parameters
n_neighborsint, default=5

Number of neighbors.

metricstring | dict, default=’riemann’

The type of metric used for distance estimation. see distance for the list of supported metric.

n_jobsint, default=1

The number of jobs to use for the computation. This works by computing each of the distance to the training set in parallel. If -1 all CPUs are used. If 1 is given, no parallel computing code is used at all, which is useful for debugging. For n_jobs below -1, (n_cpus + 1 + n_jobs) are used. Thus for n_jobs = -2, all CPUs but one are used.

See also

Kmeans
MDM
Attributes
classes_ndarray, shape (n_classes,)

Labels for each class.

covmeans_ndarray, shape (n_matrices, n_channels, n_channels)

Matrices of training set.

classmeans_ndarray, shape (n_matrices,)

Labels of training set.

__init__(n_neighbors=5, metric='riemann', n_jobs=1)

Init.

fit(X, y, sample_weight=None)

Fit (store the training data).

Parameters
Xndarray, shape (n_matrices, n_channels, n_channels)

Set of SPD matrices.

yndarray, shape (n_matrices,)

Labels for each matrix.

sample_weightNone

Not used, here for compatibility with sklearn API.

Returns
selfNearestNeighbor instance

The NearestNeighbor instance.

fit_predict(X, y)

Fit and predict in one function.

fit_transform(X, y=None, **fit_params)

Fit to data, then transform it.

Fits transformer to X and y with optional parameters fit_params and returns a transformed version of X.

Parameters
Xarray-like of shape (n_samples, n_features)

Input samples.

yarray-like of shape (n_samples,) or (n_samples, n_outputs), default=None

Target values (None for unsupervised transformations).

**fit_paramsdict

Additional fit parameters.

Returns
X_newndarray array of shape (n_samples, n_features_new)

Transformed array.

get_params(deep=True)

Get parameters for this estimator.

Parameters
deepbool, default=True

If True, will return the parameters for this estimator and contained subobjects that are estimators.

Returns
paramsdict

Parameter names mapped to their values.

predict(covtest)

Get the predictions.

Parameters
Xndarray, shape (n_matrices, n_channels, n_channels)

Set of SPD matrices.

Returns
predndarray of int, shape (n_matrices,)

Predictions for each matrix according to the closest centroid.

predict_proba(X)

Predict proba using softmax.

Parameters
Xndarray, shape (n_matrices, n_channels, n_channels)

Set of SPD matrices.

Returns
probndarray, shape (n_matrices, n_classes)

Probabilities for each class.

score(X, y, sample_weight=None)

Return 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
Xarray-like of shape (n_samples, n_features)

Test samples.

yarray-like of shape (n_samples,) or (n_samples, n_outputs)

True labels for X.

sample_weightarray-like of shape (n_samples,), default=None

Sample weights.

Returns
scorefloat

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 Pipeline). The latter have parameters of the form <component>__<parameter> so that it’s possible to update each component of a nested object.

Parameters
**paramsdict

Estimator parameters.

Returns
selfestimator instance

Estimator instance.

transform(X)

Get the distance to each centroid.

Parameters
Xndarray, shape (n_matrices, n_channels, n_channels)

Set of SPD matrices.

Returns
distndarray, shape (n_matrices, n_classes)

The distance to each centroid according to the metric.