fix masking issue in interpolate

Author: J22Melody

src/python/pose_format/numpy/pose_body.py

@@ -339,13 +339,18 @@ def interpolate(self, new_fps: int = None, kind='cubic'):
         for people in points:
             new_frames = []
             for frames in people:
-                mask = frames.transpose()[0].mask
+                mask = frames.transpose()[-1].mask
+                # print(mask)
 
                 partial_steps = ma.array(steps, mask=mask).compressed()
 
                 if partial_steps.shape[0] == 0:  # No data for this point
                     new_frames.append(np.zeros((_new_frames, frames.shape[1])))
                 else:
+                    # print(frames)
+                    # print(frames.shape)
+                    # print(frames.compressed().shape)
+                    # print(partial_steps.shape)
                     partial_frames = frames.compressed().reshape(partial_steps.shape[0], frames.shape[1])
 
                     if len(partial_steps) == 1: