Merge pull request #347 from effigies/patch-1

MRG: negative vox size check always False

Wrongly placed parenthesis always returned False for negative voxel check.  Fix and test.

Author: matthew-brett

nibabel/nifti1.py

@@ -820,7 +820,7 @@ def get_qform(self, coded=False):
         quat = self.get_qform_quaternion()
         R = quat2mat(quat)
         vox = hdr['pixdim'][1:4].copy()
-        if np.any(vox) < 0:
+        if np.any(vox < 0):
             raise HeaderDataError('pixdims[1,2,3] should be positive')
         qfac = hdr['pixdim'][0]
         if qfac not in (-1, 1):

nibabel/tests/test_nifti1.py

@@ -448,6 +448,10 @@ def test_qform(self):
         assert_true, ehdr['qform_code'] == xfas['scanner']
         ehdr.set_qform(A, xfas['aligned'])
         assert_true, ehdr['qform_code'] == xfas['aligned']
+        # Test pixdims[1,2,3] are checked for negatives
+        for dims in ((-1, 1, 1), (1, -1, 1), (1, 1, -1)):
+            ehdr['pixdim'][1:4] = dims
+            assert_raises(HeaderDataError, ehdr.get_qform)
 
     def test_sform(self):
         # Test roundtrip case