added testing for dtype at cmdline, assuming cmdline functionality. changed value output in data_diff function to allow for validation of data type

Author: chrispycheng

nibabel/cmdline/diff.py

@@ -208,8 +208,8 @@ def get_data_diff(files, max_abs=0, max_rel=0, dtype=np.float64):
 
                     diff_rec = OrderedDict()  # so that abs goes before relative
 
-                    diff_rec['abs'] = max_abs_diff
-                    diff_rec['rel'] = max_rel_diff
+                    diff_rec['abs'] = max_abs_diff.astype(dtype)
+                    diff_rec['rel'] = max_rel_diff.astype(dtype)
                     diffs1.append(diff_rec)
                 else:
                     diffs1.append(None)
@@ -274,7 +274,8 @@ def display_diff(files, diff):
     return output
 
 
-def diff(files, header_fields='all', data_max_abs_diff=None, data_max_rel_diff=None, dtype=np.float64):
+def diff(files, header_fields='all', data_max_abs_diff=None, data_max_rel_diff=None,
+         dtype=np.float64):
     assert len(files) >= 2, "Please enter at least two files"
 
     file_headers = [nib.load(f).header for f in files]

nibabel/cmdline/tests/test_utils.py

@@ -11,7 +11,7 @@
 import nibabel as nib
 import numpy as np
 from nibabel.cmdline.utils import *
-from nibabel.cmdline.diff import get_headers_diff, display_diff, main, get_data_hash_diff, get_data_diff
+from nibabel.cmdline.diff import *
 from os.path import (join as pjoin)
 from nibabel.testing import data_path
 from collections import OrderedDict
@@ -146,6 +146,16 @@ def test_get_data_diff():
                  OrderedDict([('DATA(diff 1:)', [None, {'CMP': 'incompat'}, {'CMP': 'incompat'}]),
                               ('DATA(diff 2:)', [None, None, {'CMP': 'incompat'}])]))
 
+    test_return = get_data_diff([test_array, test_array_2], dtype=np.float32)
+    assert_equal(type(test_return['DATA(diff 1:)'][1]['abs']), np.float32)
+    assert_equal(type(test_return['DATA(diff 1:)'][1]['rel']), np.float32)
+
+    test_return_2 = get_data_diff([test_array, test_array_2, test_array_3])
+    assert_equal(type(test_return_2['DATA(diff 1:)'][1]['abs']), np.float64)
+    assert_equal(type(test_return_2['DATA(diff 1:)'][1]['rel']), np.float64)
+    assert_equal(type(test_return_2['DATA(diff 2:)'][2]['abs']), np.float64)
+    assert_equal(type(test_return_2['DATA(diff 2:)'][2]['rel']), np.float64)
+
 
 def test_main():
     test_names = [pjoin(data_path, f)