Merge pull request #125 from matthew-brett/pydicom-0p7-fixes

BF: make compatible with pydicom 0.9.7

Pydicom 0.9.7 returns some fields as Python Decimals, when previously
they were floats. This causes a mess when using values in an array,
because the array becomes objects rather than floats, and, well, it
doesn't go well. Tests pass for me with pydicom 0.9.5 through 0.9.7
with these changes.

Author: matthew-brett

nibabel/nicom/dicomwrappers.py

@@ -130,6 +130,8 @@ def image_orient_patient(self):
         iop = self.get('ImageOrientationPatient')
         if iop is None:
             return None
+        # Values are python Decimals in pydicom 0.9.7
+        iop = np.array((map(float, iop)))
         return np.array(iop).reshape(2,3).T
 
     @one_time
@@ -180,6 +182,9 @@ def voxel_sizes(self):
             zs = self.get('SliceThickness')
             if zs is None:
                 zs = 1
+        # Protect from python decimals in pydicom 0.9.7
+        zs = float(zs)
+        pix_space = map(float, pix_space)
         return tuple(pix_space + [zs])
 
     @one_time
@@ -198,7 +203,8 @@ def image_position(self):
         ipp = self.get('ImagePositionPatient')
         if ipp is None:
             return None
-        return np.array(ipp)
+        # Values are python Decimals in pydicom 0.9.7
+        return np.array(map(float, ipp))
 
     @one_time
     def slice_indicator(self):
@@ -558,13 +564,15 @@ def image_position(self):
         img_pos : (3,) array
            position in mm of voxel (0,0,0) in Mosaic array
         '''
-        ipp = self.get('ImagePositionPatient')
+        ipp = super(MosaicWrapper, self).image_position
         # mosaic image size
         md_rows, md_cols = (self.get('Rows'), self.get('Columns'))
         iop = self.image_orient_patient
         pix_spacing = self.get('PixelSpacing')
         if None in (ipp, md_rows, md_cols, iop, pix_spacing):
             return None
+        # PixelSpacing values are python Decimal in pydicom 0.9.7
+        pix_spacing = np.array(map(float, pix_spacing))
         # size of mosaic array before rearranging to 3D.
         md_rc = np.array([md_rows, md_cols])
         # size of slice array after reshaping to 3D