fix SSD's filters_ shape inconsistency

Author: Genuster

mne/decoding/ssd.py

@@ -95,9 +95,9 @@ class SSD(_GEDTransformer):
 
     Attributes
     ----------
-    filters_ : array, shape (n_channels, n_components)
+    filters_ : array, shape (n_channels or less, n_channels)
         The spatial filters to be multiplied with the signal.
-    patterns_ : array, shape (n_components, n_channels)
+    patterns_ : array, shape (n_channels or less, n_channels)
         The patterns for reconstructing the signal from the filtered data.
 
     References
@@ -272,13 +272,12 @@ def fit(self, X, y=None):
         # project back to sensor space
         self.filters_ = np.matmul(rank_proj, eigvects_[:, ix])
         self.patterns_ = np.linalg.pinv(self.filters_)
+        # Need to unify with Xdawn and CSP as they store it as (n_components, n_chs)
+        self.filters_ = self.filters_.T
 
         old_filters = self.filters_
         old_patterns = self.patterns_
         super().fit(X, y)
-        # SSD, as opposed to CSP and Xdawn stores filters as (n_chs, n_components)
-        # So need to transpose into (n_components, n_chs)
-        self.filters_ = self.filters_.T
 
         np.testing.assert_allclose(self.eigvals_, self.evals_)
         np.testing.assert_allclose(old_filters, self.filters_)
@@ -287,7 +286,7 @@ def fit(self, X, y=None):
         # We assume that ordering by spectral ratio is more important
         # than the initial ordering. This ordering should be also learned when
         # fitting.
-        X_ssd = self.filters_.T @ X[..., self.picks_, :]
+        X_ssd = self.filters_ @ X[..., self.picks_, :]
         sorter_spec = slice(None)
         if self.sort_by_spectral_ratio:
             _, sorter_spec = self.get_spectral_ratio(ssd_sources=X_ssd)
@@ -315,7 +314,7 @@ def transform(self, X):
         if self.return_filtered:
             X_aux = X[..., self.picks_, :]
             X = filter_data(X_aux, self.sfreq_, **self.filt_params_signal)
-        X_ssd = self.filters_.T @ X[..., self.picks_, :]
+        X_ssd = self.filters_ @ X[..., self.picks_, :]
         X_ssd = X_ssd[..., self.sorter_spec_, :][..., : self.n_components, :]
         return X_ssd