Add partial_amplitudes as an output of mrDMD

Author: Takaya Uchida

pydmd/mrdmd.py

@@ -386,6 +386,26 @@ def partial_eigs(self, level, node=None):
             [self.dmd_tree[level, leaf].eigs for leaf in leaves]
         )
 
+    def partial_amplitudes(self, level, node=None):
+        """
+        Return the amplitudes of the specific `level` and of the specific
+        `node`; if `node` is not specified, the method returns the amplitudes
+        of the given `level` (all the nodes).
+
+        :param int level: the index of the level from where the amplitudes are
+            extracted.
+        :param int node: the index of the node from where the amplitudes are
+            extracted; if None, the amplitudes are extracted from all the
+            nodes of the given level. Default is None.
+
+        :return: the selected eigs
+        :rtype: numpy.ndarray
+        """
+        leaves = self.dmd_tree.index_leaves(level) if node is None else [node]
+        return np.concatenate(
+            [self.dmd_tree[level, leaf].amplitudes for leaf in leaves]
+        )
+    
     def partial_reconstructed_data(self, level, node=None):
         """
         Return the reconstructed data computed using the modes and the time