Code reorganization, comment editing.

Author: Ben Cipollini

nibabel/funcs.py

@@ -94,13 +94,16 @@ def concat_images(images, check_affines=True, axis=None):
     Parameters
     ----------
     images : sequence
-       sequence of ``SpatialImage`` or filenames\s
+       sequence of ``SpatialImage`` or filenames of the same dimensionality\s
     check_affines : {True, False}, optional
        If True, then check that all the affines for `images` are nearly
        the same, raising a ``ValueError`` otherwise.  Default is True
     axis : None or int, optional
-        If None, concatenates on the 4th dimension.
-        If not None, concatenates on the specified dimension [-2 to 3).
+        If None, concatenates on a new dimension.  This rrequires all images
+           to be the same shape).
+        If not None, concatenates on the specified dimension.  This requires
+           all images to be the same shape, except on the specified dimension.
+           For 4D images, axis must be between -2 and 3.
     Returns
     -------
     concat_img : ``SpatialImage``
@@ -110,7 +113,7 @@ def concat_images(images, check_affines=True, axis=None):
 
     n_imgs = len(images)
     if n_imgs == 0:
-        raise ValueError('Cannot concatenate an empty list of images.')
+        raise ValueError("Cannot concatenate an empty list of images.")
 
     for i, img in enumerate(images):
         if not hasattr(img, 'get_data'):

nibabel/tests/test_funcs.py

@@ -110,11 +110,12 @@ def test_concat():
                         try:
                             all_imgs = concat_images([img0, img1],
                                                      **concat_imgs_kwargs)
-                            assert_array_equal(all_imgs.get_data(), all_data)
-                            assert_array_equal(all_imgs.affine, affine)
-                            assert_false(expect_error, "Expected a concatenation error, but got none.")
                         except ValueError as ve:
                             assert_true(expect_error, ve.message)
+                        else:
+                            assert_false(expect_error, "Expected a concatenation error, but got none.")
+                            assert_array_equal(all_imgs.get_data(), all_data)
+                            assert_array_equal(all_imgs.affine, affine)
 
                         # check that not-matching affines raise error
                         assert_raises(ValueError, concat_images, [img0, img2], **concat_imgs_kwargs)
@@ -123,12 +124,12 @@ def test_concat():
                         # except if check_affines is False
                         try:
                             all_imgs = concat_images([img0, img1], **concat_imgs_kwargs)
-                            assert_array_equal(all_imgs.get_data(), all_data)
-                            assert_array_equal(all_imgs.affine, affine)
-                            assert_false(expect_error, "Expected a concatenation error, but got none.")
                         except ValueError as ve:
                             assert_true(expect_error, ve.message)
-
+                        else:
+                            assert_false(expect_error, "Expected a concatenation error, but got none.")
+                            assert_array_equal(all_imgs.get_data(), all_data)
+                            assert_array_equal(all_imgs.affine, affine)
 
 
 def test_closest_canonical():