FMRILinearModel handles the case where contrasts are null for some fmri sessions

Yannick Schwartz · matthew-brett · commit 41540d6e0290 · 2013-01-22T12:07:12.000-08:00
diff --git a/nipy/modalities/fmri/glm.py b/nipy/modalities/fmri/glm.py
@@ -32,6 +32,8 @@
 
 import numpy as np
 
+from warnings import warn
+
 import scipy.stats as sps
 
 from nibabel import load, Nifti1Image
@@ -561,8 +563,11 @@ def contrast(self, contrasts, con_id='', contrast_type=None, output_z=True,
                 'contrasts must be a sequence of %d session contrasts' %
                 len(self.glms))
 
+        contrast_ = None
         for i, (glm, con) in enumerate(zip(self.glms, contrasts)):
-            if i == 0:
+            if np.all(con == 0):
+                warn('Contrast for session %d is null' % i)
+            elif not contrast_:
                 contrast_ = glm.contrast(con, contrast_type)
             else:
                 contrast_ = contrast_ + glm.contrast(con, contrast_type)
