doc: annotate how cutoff is being created
@@ -515,6 +515,7 @@ class DenseRunVariable(BIDSVariable):
if sampling_rate < self.sampling_rate:
# Downsampling, so filter the signal
from scipy.signal import butter, filtfilt
+ # cutoff = new Nyqist / old Nyquist
b, a = butter(5, (sampling_rate / 2.0) / (self.sampling_rate / 2.0),
btype='low', output='ba', analog=False)
y = filtfilt(b, a, self.values.values.ravel())
