Avoid lowpass=0 in brainvision data (#10517)

* Avoid lowpass=0 in brainvision data

* Add changelog

* Update doc/changes/latest.inc

Co-authored-by: Stefan Appelhoff <stefan.appelhoff@mailbox.org>

Co-authored-by: Alessandro Tonin <alessandro.tonin@wysscenter.ch>
Co-authored-by: Stefan Appelhoff <stefan.appelhoff@mailbox.org>
Co-authored-by: Eric Larson <larson.eric.d@gmail.com>

doc/changes/latest.inc

@@ -27,6 +27,8 @@ Enhancements
 
 Bugs
 ~~~~
+- Fix bug in :func:`mne.io.read_raw_brainvision` when BrainVision data are acquired with the Brain Products "V-Amp" amplifier and disabled lowpass filter is marked with value ``0`` (:gh:`10517` by :newcontrib:`Alessandro Tonin`)
+
 - Fix bug in :func:`mne.pick_types` and related methods where ``csd=True`` was not passed handled properly (:gh:`10470` by :newcontrib:`Matthias Dold`)
 
 - Fix bug where plots produced using the ``'qt'`` / ``mne_qt_browser`` backend could not be added using :meth:`mne.Report.add_figure` (:gh:`10485` by `Eric Larson`_)

doc/changes/names.inc

@@ -426,6 +426,8 @@
 
 .. _Senwen Deng: https://snwn.de
 
+.. _Alessandro Tonin: https://wysscenter.ch/team/alessandro-tonin
+
 .. _Michiru Kaneda: https://github.com/rcmdnk
 
 .. _Scott Huberty:  https://orcid.org/0000-0003-2637-031X

mne/io/brainvision/brainvision.py

@@ -725,7 +725,7 @@ def _get_vhdr_info(vhdr_fname, eog, misc, scale):
         if len(lowpass) == 0:
             pass
         elif len(set(lowpass)) == 1:
-            if lowpass[0] in ('NaN', 'Off'):
+            if lowpass[0] in ('NaN', 'Off', '0'):
                 pass  # Placeholder for future use. Lowpass set in _empty_info
             else:
                 info['lowpass'] = float(lowpass[0])
@@ -738,7 +738,7 @@ def _get_vhdr_info(vhdr_fname, eog, misc, scale):
             if lp_s:
                 # We convert channels with disabled filters to having
                 # infinitely relaxed / no filters
-                lowpass = [float(filt) if filt not in ('NaN', 'Off')
+                lowpass = [float(filt) if filt not in ('NaN', 'Off', '0')
                            else 0.0 for filt in lowpass]
                 info['lowpass'] = np.min(np.array(lowpass, dtype=np.float64))
                 try:
@@ -760,7 +760,7 @@ def _get_vhdr_info(vhdr_fname, eog, misc, scale):
             else:
                 # We convert channels with disabled filters to having
                 # infinitely relaxed / no filters
-                lowpass = [float(filt) if filt not in ('NaN', 'Off')
+                lowpass = [float(filt) if filt not in ('NaN', 'Off', '0')
                            else np.Inf for filt in lowpass]
                 info['lowpass'] = np.max(np.array(lowpass, dtype=np.float64))