The frequencies in return "con" is different than what was given in the arguments in function spectral_connectivity_epochs

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1

Hello,
I want to get coherence from 1hz to 45 hz. But with the codes below, the frequencies in con con.freqs always end up with 2 till 45Hz. I tried cwt_freqs=np.arange(0,46), cwt_n_cycles=np.linspace(2,10,46) as well, still 1hz was not included in the result. Can someone tell me why?
My raw was high-passed by 0.5Hz.
Thanks!

  • MNE version: 1.1
  • operating system: Windows 11
        con = spectral_connectivity_epochs(
            epochs,method='coh',indices=None,mode='cwt_morlet',
            sfreq=raw.info['sfreq'],cwt_freqs=np.arange(1,46), cwt_n_cycles=np.linspace(2,10,45)
            )

In this mne example, con.freqs also starts with 9Hz not 7Hz as given in the arguments.

2

I wonder if it has to do with the number of cycles at the lower frequency available in the length of the epochs?
In the example you linked, the lower value of cwt_n_cycles is 1. Perhaps more than one cycle (or one complete cycle) is required to perform frequency decomp using Morlet wavelets?