add _has_source_detector_distances

Author: Kallemakela

mne/preprocessing/nirs/__init__.py

@@ -5,6 +5,7 @@
 # Copyright the MNE-Python contributors.
 
 from .nirs import (
+    _has_source_detector_distances,
     short_channels,
     source_detector_distances,
     _check_channels_ordered,

mne/preprocessing/nirs/nirs.py

@@ -62,6 +62,12 @@ def short_channels(info, threshold=0.01):
     return source_detector_distances(info) < threshold
 
 
+def _has_source_detector_distances(info, picks=None):
+    """Return True if source-detector distances can be computed."""
+    distances = source_detector_distances(info, picks=picks)
+    return len(distances) > 0 and np.isfinite(distances).all() and np.all(distances > 0)
+
+
 def _channel_frequencies(info):
     """Return the light frequency for each channel."""
     # Only valid for fNIRS data before conversion to haemoglobin

mne/preprocessing/nirs/tests/test_nirs.py

@@ -18,6 +18,7 @@
     _check_channels_ordered,
     _fnirs_optode_names,
     _fnirs_spread_bads,
+    _has_source_detector_distances,
     _optode_position,
     _validate_nirs_info,
     beer_lambert_law,
@@ -538,6 +539,22 @@ def test_optode_names():
     assert_array_equal(det_names, [f"D{n}" for n in ["1", "11", "17"]])
 
 
+def test_has_source_detector_distances():
+    """Ensure source-detector distance availability is detected."""
+    ch_names = ["S1_D1 760", "S1_D1 850", "S2_D1 760", "S2_D1 850"]
+    info = create_info(ch_names=ch_names, ch_types=np.repeat("fnirs_od", 4), sfreq=1.0)
+    assert not _has_source_detector_distances(info)
+    for idx in range(2):
+        info["chs"][idx]["loc"][3:6] = [0.0, 0.0, 0.0]
+        info["chs"][idx]["loc"][6:9] = [0.03, 0.0, 0.0]
+    assert _has_source_detector_distances(info, picks=[0, 1])
+    assert not _has_source_detector_distances(info)  # some chs missing
+    for idx in range(2, 4):
+        info["chs"][idx]["loc"][3:6] = [0.01, 0.0, 0.0]
+        info["chs"][idx]["loc"][6:9] = [0.04, 0.0, 0.0]
+    assert _has_source_detector_distances(info)
+
+
 @testing.requires_testing_data
 def test_optode_loc():
     """Ensure optode location extraction is correct."""