Assertion error if raw has HP/LP set, but config specifies lower/higher HP/LP

[skjerns]

Our MEG by default records with HP=0.1 and LP=330.

In my config.conf, I have mistakenly set l_freq=0.05, which now raises an AssertionError as the filtering will not work.

Probably there should be a check if the requested highpass/lowpass are actually feasable?

l_freq: float = 0.05  # Apply high-pass filter at 0.1 Hz
h_freq: Optional[float] = None  # Disable low-pass filter

console output:

┌────────┬ preprocessing/_06a1_fit_ica ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
│17:54:36│ ⏳️ sub-01 Processing raw data from sub-01_task-main_proc-filt_raw.fif
│17:54:37│  sub-01 A critical error occurred. The error message was: 

Starting post-mortem debugger.
<traceback object at 0x7fcaa857a880>
> /zi/home/simon.kern/anaconda3/lib/python3.11/site-packages/mne_bids_pipeline/steps/preprocessing/_06a1_fit_ica.py(104)run_ica()
-> assert np.allclose(raw.info["highpass"], cfg.l_freq)
# ->> I figured that the recording MEG sets a highpass of 0.1, so my 0.05 don't have much effect. `raw['highpass'] is indeed 0.1, while `cfg.l_freq=0.05`

[welcome]

Hello! 👋 Thanks for opening your first issue here! ❤️ We will try to get back to you soon. 🚴🏽‍♂️

[larsoner]

Yeah it might be better to check if the bound is less than the current info["highpass"]. Safest would be to make it an error if it is. We could be more permissive and make it a a warning, though, in case you want more attenuation than DAQ highpass provides. But in either case I agree that the current AssertionError is not super helpful!