I am training a four-class motor imagery classifier, I partitioned the dataset into epochs based on events(epochs = mne.Epochs(raw, events, event_id, tmin, tmax, proj=True, baseline=(0., 0.1), preload=True)) and obtained data from epochs using ‘get_data'(data = epochs.get_data()). I performed wavelet packet decomposition (WPD) on the data to obtain ‘wpd_data’.