less mysterious error messages

Author: Shoshana Berleant

nipype/algorithms/confounds.py

@@ -409,6 +409,11 @@ class TCompCor(CompCor):
     def _run_interface(self, runtime):
         imgseries = nb.load(self.inputs.realigned_file).get_data()
 
+        if imgseries.ndim != 4:
+            raise ValueError('tCompCor expected a 4-D nifti file. Input {} has {} dimensions '
+                             '(shape {})'
+                             .format(self.inputs.realigned_file, imgseries.ndim, imgseries.shape))
+
         # From the paper:
         # "For each voxel time series, the temporal standard deviation is
         # defined as the standard deviation of the time series after the removal

nipype/algorithms/tests/test_compcor.py

@@ -84,8 +84,9 @@ def test_tcompcor_asymmetric_dim(self):
     def test_compcor_bad_input_shapes(self):
         shape_less_than = (1, 2, 2, 5) # dim 0 is < dim 0 of self.mask_file (2)
         shape_more_than = (3, 3, 3, 5) # dim 0 is > dim 0 of self.mask_file (2)
+        bad_dims = (2, 2, 2) # not 4-D
 
-        for data_shape in (shape_less_than, shape_more_than):
+        for data_shape in (shape_less_than, shape_more_than, bad_dims):
             data_file = utils.save_toy_nii(np.zeros(data_shape), 'temp.nii')
             interface = CompCor(realigned_file=data_file, mask_file=self.mask_file)
             self.assertRaisesRegexp(ValueError, "dimensions", interface.run)