Replace mapImage with image_like

Author: effigies

nibabel/__init__.py

@@ -58,6 +58,7 @@
 from .freesurfer import MGHImage
 from .funcs import (squeeze_image, concat_images, four_to_three,
                     as_closest_canonical)
+from .spatialimages import image_like
 from .orientations import (io_orientation, orientation_affine,
                            flip_axis, OrientationError,
                            apply_orientation, aff2axcodes)

nibabel/spatialimages.py

@@ -874,7 +874,9 @@ def __getitem__(self):
                         "`img.get_data()[slice]`")
 
 
-def mapImage(func, img):
-    """Map a function onto image data"""
-    return img.__class__(func(img.get_data()), img.affine, img.header.copy(),
+def image_like(img, data):
+    ''' Create new SpatialImage with metadata of `img`, and data
+    contained in `data`.
+    '''
+    return img.__class__(data, img.affine, img.header.copy(),
                          extra=img.extra.copy())

nibabel/tests/test_spatialimages.py

@@ -13,7 +13,7 @@
 import numpy as np
 
 from ..spatialimages import (Header, SpatialImage, HeaderDataError,
-                             ImageDataError, mapImage)
+                             ImageDataError, image_like)
 
 from unittest import TestCase
 
@@ -384,7 +384,11 @@ def test_load_mmap(self):
                 assert_raises(ValueError, func, param1, mmap='r+')
 
 
-def test_mapImage():
-    img = SpatialImage(np.zeros((2, 3, 4)), np.eye(4))
-    assert np.unique(mapImage(lambda x: x + 1, img).get_data()) == \
-        np.array([1.0])
+def test_image_like():
+    zeros = SpatialImage(np.zeros((2, 3, 4)), np.eye(4))
+    ones = image_like(zeros, np.ones((2, 3, 4)))
+
+    assert np.all(ones.dataobj != zeros.dataobj)
+    assert np.all(ones.affine == zeros.affine)
+    assert ones.header == zeros.header
+    assert ones.extra == zeros.extra