pyriemann.utils.mean.mean_wasserstein¶
- pyriemann.utils.mean.mean_wasserstein(covmats, tol=0.001, maxiter=50, init=None, sample_weight=None)¶
Mean of SPD matrices according to the Wasserstein metric.
Wasserstein mean is obtained by an iterative procedure where the update is [1]:
\[\mathbf{K} = \left(\sum_i \left( \mathbf{K} \mathbf{C}_i \mathbf{K} \right)^{1/2} \right)^{1/2}\]with \(\mathbf{K} = \mathbf{C}^{1/2}\).
- Parameters
- covmatsndarray, shape (n_matrices, n_channels, n_channels)
Set of SPD matrices.
- tolfloat, default=10e-4
The tolerance to stop the gradient descent.
- maxiterint, default=50
The maximum number of iterations.
- initNone | ndarray, shape (n_channels, n_channels), default=None
A SPD matrix used to initialize the gradient descent. If None the Euclidean mean is used.
- sample_weightNone | ndarray, shape (n_matrices,), default=None
Weights for each matrix. If None, it uses equal weights.
- Returns
- Cndarray, shape (n_channels, n_channels)
Wasserstein mean.
References
- 1
Geometric Radar Processing based on Frechet distance: Information geometry versus Optimal Transport Theory F. Barbaresco. 12th International Radar Symposium (IRS), October 2011