ASR transform fails (unexpected zi shape)

Hello! I am trying to apply ASR to some EEG data recorded at our lab with EEGLAB. We are using MNE for the analyses and we wanted to incorporate ASR as a preprocessing step. I was currently running the asr example code:

# Get data array for ASR
raw_array = raw.get_data()

# Train ASR
asr = ASR(method='euclid')
train_idx = np.arange(0 * sfreq, 30 * sfreq, dtype=int) # 30s period
_, sample_mask = asr.fit(raw_array[:, train_idx])

# Apply a sliding window to the data
X = sliding_window(raw_array, window=int(sfreq), step=int(sfreq))
Y = np.zeros_like(X)
for i in range(X.shape[1]):
    Y[:, i, :] = asr.transform(X[:, i, :])

And I got the following error:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-63-b37fc0c9f43f> in <module>
     11 Y = np.zeros_like(X)
     12 for i in range(X.shape[1]):
---> 13     Y[:, i, :] = asr.transform(X[:, i, :])

~/gitrepos/python-meegkit/meegkit/asr.py in transform(self, X, y, **kwargs)
    221         # Yulewalk-filtered data (optional).
    222         X_filt, self.zi_ = yulewalk_filter(
--> 223             X, sfreq=self.sfreq, ab=self.ab_, zi=self.zi_)
    224 
    225         if not self._fitted:

~/gitrepos/python-meegkit/meegkit/utils/asr.py in yulewalk_filter(X, sfreq, zi, ab, axis)
    317     if zi is None:
    318         zi = signal.lfilter_zi(B, A)
--> 319         out, zf = signal.lfilter(B, A, X, zi=zi[:, None] * X[:, 0], axis=axis)
    320     else:
    321         out, zf = signal.lfilter(B, A, X, zi=zi, axis=axis)

~/anaconda3/envs/mne/lib/python3.7/site-packages/scipy/signal/signaltools.py in lfilter(b, a, x, axis, zi)
   1907             return sigtools._linear_filter(b, a, x, axis)
   1908         else:
-> 1909             return sigtools._linear_filter(b, a, x, axis, zi)
   1910 
   1911 

ValueError: Unexpected shape for zi:  expected (32,8), found (8,32).

My understanding of the analysis is not very deep, but after looking around in scipy documentation and the repo’s code I found that this ‘zi’ parameter is calculated automatically before being passed to the lfilter function. Being so, I am a bit confused by the fact that it has unexpected shape. Any ideas? Thanks!

[nbara]

Glad to hear this ! Sorry for taking more than a month to reply (I usually get notifications for issues but this one slipped by)

[nbara]

Nevermind, I think I have a fix in #15. Can you please try to checkout nb/fix-issue-10 and report back if it solves your issue?