pyriemann.estimation.Kernels¶
- class pyriemann.estimation.Kernels(metric='linear', n_jobs=None, **kwds)¶
Estimation of kernel matrices between channels of time series.
Perform a kernel matrix estimation for each given time series, evaluating a kernel function between each pair of channels (rather than between pairs of time samples) and allowing to extract nonlinear channel relationship [1].
For an input time series \(X \in \mathbb{R}^{c \times t}\), composed of \(c\) channels and \(t\) time samples, kernel function \(\kappa()\) is computed between channels \(i\) and \(j\):
\[K_{i,j} = \kappa \left( X[i], X[j] \right)\]Linear kernel is related to
pyriemann.estimation.Covariances
[1], but this class allows to generalize to nonlinear relationships.- Parameters:
- metricstring, default=’linear’
The metric to use when computing kernel function between channels [2]: “linear”, “poly”, “polynomial”, “rbf”, “laplacian”, “cosine”.
- n_jobsint, default=None
The number of jobs to use for the computation [2]. This works by breaking down the pairwise matrix into n_jobs even slices and computing them in parallel.
- **kwdsdict
Any further parameters are passed directly to the kernel function [2].
See also
Notes
Added in version 0.4.
References
[1] (1,2)Beyond Covariance: Feature Representation with Nonlinear Kernel Matrices L. Wang, J. Zhang, L. Zhou, C. Tang, W Li. ICCV, 2015.
- __init__(metric='linear', n_jobs=None, **kwds)¶
Init.
- fit(X, y=None)¶
Fit.
Do nothing. For compatibility purpose.
- Parameters:
- Xndarray, shape (n_matrices, n_channels, n_times)
Multi-channel time-series.
- yNone
Not used, here for compatibility with sklearn API.
- Returns:
- selfKernels instance
The Kernels instance.
- fit_transform(X, y=None)¶
Fit and transform in a single function.
Estimate kernel matrices from time series.
- Parameters:
- Xndarray, shape (n_matrices, n_channels, n_times)
Multi-channel time-series.
- yNone
Not used, here for compatibility with sklearn API.
- Returns:
- X_newndarray, shape (n_matrices, n_channels, n_channels)
Kernel matrices.
- get_metadata_routing()¶
Get metadata routing of this object.
Please check User Guide on how the routing mechanism works.
- Returns:
- routingMetadataRequest
A
MetadataRequest
encapsulating routing information.
- 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.
- set_output(*, transform=None)¶
Set output container.
See Introducing the set_output API for an example on how to use the API.
- Parameters:
- transform{“default”, “pandas”, “polars”}, default=None
Configure output of transform and fit_transform.
“default”: Default output format of a transformer
“pandas”: DataFrame output
“polars”: Polars output
None: Transform configuration is unchanged
Added in version 1.4: “polars” option was added.
- Returns:
- selfestimator instance
Estimator instance.
- 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)¶
Estimate kernel matrices from time series.
- Parameters:
- Xndarray, shape (n_matrices, n_channels, n_times)
Multi-channel time-series.
- Returns:
- X_newndarray, shape (n_matrices, n_channels, n_channels)
Kernel matrices.
Examples using pyriemann.estimation.Kernels
¶

Classify fNIRS data with block diagonal matrices for HbO and HbR