# Help with custom fNIRS montage **URL:** \ **Category:** Support & Discussions\ **Tags:** fnirs\ **Created:** [January 8, 2024, 11:06pm UTC](https://mne.discourse.group/t/help-with-custom-fnirs-montage/8108 "2024-01-08T23:06:28Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![librethinker](https://avatars.discourse-cdn.com/v4/letter/l/67e7ee/32.png) [@librethinker](https://mne.discourse.group/u/librethinker)\ **Post date:** [January 8, 2024, 11:06pm UTC](https://mne.discourse.group/t/help-with-custom-fnirs-montage/8108/1 "2024-01-08T23:06:28Z")
Hey all, I try to get the correct sources and detector positions for my dataset into mne-nirs. I have 8 sources and 8 detectors and their positions correspond to 10-20 positions. Here ist my mapping: ```python mapping = { 'S1_D1 760': 'CP5_TP7 760', 'S1_D2 760': 'CP5_C5 760', 'S2_D1 760': 'T7_TP7 760', 'S2_D2 760': 'T7_C5 760', 'S2_D3 760': 'T7_FT7 760', 'S3_D2 760': 'FC5_C5 760', 'S3_D3 760': 'FC5_FT7 760', 'S3_D4 760': 'FC5_F5 760', 'S4_D3 760': 'F7_FT7 760', 'S4_D4 760': 'F7_F5 760', 'S5_D5 760': 'F8_F6 760', 'S5_D6 760': 'F8_FT8 760', 'S6_D5 760': 'FC6_F6 760', 'S6_D6 760': 'FC6_FT8 760', 'S6_D7 760': 'FC6_C6 760', 'S7_D6 760': 'T8_FT8 760', 'S7_D7 760': 'T8_C6 760', 'S7_D8 760': 'T8_TP8 760', 'S8_D7 760': 'CP6_C6 760', 'S8_D8 760': 'CP6_TP8 760', 'S1_D1 850': 'CP5_TP7 850', 'S1_D2 850': 'CP5_C5 850', 'S2_D1 850': 'T7_TP7 850', 'S2_D2 850': 'T7_C5 850', 'S2_D3 850': 'T7_FT7 850', 'S3_D2 850': 'FC5_C5 850', 'S3_D3 850': 'FC5_FT7 850', 'S3_D4 850': 'FC5_F5 850', 'S4_D3 850': 'F7_FT7 850', 'S4_D4 850': 'F7_F5 850', 'S5_D5 850': 'F8_F6 850', 'S5_D6 850': 'F8_FT8 850', 'S6_D5 850': 'FC6_F6 850', 'S6_D6 850': 'FC6_FT8 850', 'S6_D7 850': 'FC6_C6 850', 'S7_D6 850': 'T8_FT8 850', 'S7_D7 850': 'T8_C6 850', 'S7_D8 850': 'T8_TP8 850', 'S8_D7 850': 'CP6_C6 850', 'S8_D8 850': 'CP6_TP8 850' } ``` My question is, how can I get the correct 10-20 positions imported for the source-detector pairs? I already tried to rename the channels according to my mapping and set the standard\_1020 montage afterwards but I get the following error for `raw_intensity.set_montage("standard_1020")`: ```python --------------------------------------------------------------------------- AttributeError Traceback (most recent call last) Cell In[74], line 2 1 mne.rename_channels(raw_intensity.info, mapping) ----> 2 raw_intensity.set_montage("standard_1020") File :12, in set_montage(self, montage, match_case, match_alias, on_missing, verbose) File ~\AppData\Roaming\Python\Python312\site-packages\mne\_fiff\meas_info.py:427, in MontageMixin.set_montage(self, montage, match_case, match_alias, on_missing, verbose) 424 from ..channels.montage import _set_montage 426 info = self if isinstance(self, Info) else self.info --> 427 _set_montage(info, montage, match_case, match_alias, on_missing) 428 return self File ~\AppData\Roaming\Python\Python312\site-packages\mne\channels\montage.py:1337, in _set_montage( ***failed resolving arguments*** ) 1335 fnirs_picks = _picks_to_idx(info, "fnirs", allow_empty=True) 1336 if len(fnirs_picks) > 0: -> 1337 _set_montage_fnirs(info, mnt_head) File ~\AppData\Roaming\Python\Python312\site-packages\mne\channels\montage.py:1089, in _set_montage_fnirs(info, montage) 1086 from ..preprocessing.nirs import _validate_nirs_info 1088 # Validate that the fNIRS info is correctly formatted -> 1089 picks = _validate_nirs_info(info) 1091 # Modify info['chs'][#]['loc'] in place 1092 num_ficiduals = len(montage.dig) - len(montage.ch_names) File ~\AppData\Roaming\Python\Python312\site-packages\mne\preprocessing\nirs\nirs.py:264, in _validate_nirs_info(info, throw_errors, fnirs, which, check_bads, allow_empty) 260 if not len(pick_types(info, fnirs=fnirs)): 261 raise RuntimeError( 262 f"{which} must operate on {kind} data, but none was found." 263 ) --> 264 freqs = np.unique(_channel_frequencies(info)) 265 if freqs.size > 0: 266 pair_vals = freqs File ~\AppData\Roaming\Python\Python312\site-packages\mne\preprocessing\nirs\nirs.py:76, in _channel_frequencies(info) 74 freqs = list() 75 for pick in picks: ---> 76 freqs.append(round(float(_S_D_F_RE.match(info["ch_names"][pick]).groups()[2]))) 77 return np.array(freqs, int) AttributeError: 'NoneType' object has no attribute 'groups' ``` Thank you for any help! ---
**Author:** ![librethinker](https://avatars.discourse-cdn.com/v4/letter/l/67e7ee/32.png) [@librethinker](https://mne.discourse.group/u/librethinker)\ **Post date:** [January 9, 2024, 10:58pm UTC](https://mne.discourse.group/t/help-with-custom-fnirs-montage/8108/2 "2024-01-09T22:58:30Z")
Solved it by creating my own montage file based on [standard\_1020.elc](https://github.com/mne-tools/mne-python/blob/0b503d8b64bd1383eee0450c3998700ad354a1ef/mne/channels/data/montages/standard_1020.elc) and loading it with `mne.channels.read_custom_montage`