From 963aee021194bf1346502bb9200a0a758ada3ce7 Mon Sep 17 00:00:00 2001
From: "Christopher J. Markiewicz" <effigies@bu.edu>
Date: Tue, 24 Mar 2015 16:55:28 -0400
Subject: [PATCH 1/2] Add image_like function for generic SpatialImage

---
 nibabel/__init__.py                 |  1 +
 nibabel/spatialimages.py            |  8 ++++++++
 nibabel/tests/test_spatialimages.py | 12 +++++++++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/nibabel/__init__.py b/nibabel/__init__.py
index fca22ccc99..25b14d398f 100644
--- a/nibabel/__init__.py
+++ b/nibabel/__init__.py
@@ -72,6 +72,7 @@ def setup_test():
 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)
diff --git a/nibabel/spatialimages.py b/nibabel/spatialimages.py
index ede0820065..b749cdc7b7 100644
--- a/nibabel/spatialimages.py
+++ b/nibabel/spatialimages.py
@@ -634,3 +634,11 @@ def as_reoriented(self, ornt):
         new_aff = self.affine.dot(inv_ornt_aff(ornt, self.shape))
 
         return self.__class__(t_arr, new_aff, self.header)
+
+
+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())
diff --git a/nibabel/tests/test_spatialimages.py b/nibabel/tests/test_spatialimages.py
index b0f571023d..b8569543b4 100644
--- a/nibabel/tests/test_spatialimages.py
+++ b/nibabel/tests/test_spatialimages.py
@@ -16,7 +16,7 @@
 
 from io import BytesIO
 from ..spatialimages import (SpatialHeader, SpatialImage, HeaderDataError,
-                             Header, ImageDataError)
+                             Header, ImageDataError, image_like)
 from ..imageclasses import spatial_axes_first
 
 from unittest import TestCase
@@ -659,3 +659,13 @@ class MyHeader(Header):
 
         MyHeader()
         assert_equal(len(w), 1)
+
+
+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

From cc5b2bb219995bf4578a8717db18fad67b89edb0 Mon Sep 17 00:00:00 2001
From: "Christopher J. Markiewicz" <effigies@bu.edu>
Date: Sat, 6 Jun 2015 23:10:55 -0400
Subject: [PATCH 2/2] Add optional data parameter to from_image, call
 from_image from image_like

---
 nibabel/spatialimages.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/nibabel/spatialimages.py b/nibabel/spatialimages.py
index b749cdc7b7..4f658fa91a 100644
--- a/nibabel/spatialimages.py
+++ b/nibabel/spatialimages.py
@@ -537,7 +537,7 @@ def get_affine(self):
         return self.affine
 
     @classmethod
-    def from_image(klass, img):
+    def from_image(klass, img, data=None):
         ''' Class method to create new instance of own class from `img`
 
         Parameters
@@ -551,7 +551,7 @@ def from_image(klass, img):
         cimg : ``spatialimage`` instance
            Image, of our own class
         '''
-        return klass(img.dataobj,
+        return klass(img.dataobj if data is None else data,
                      img.affine,
                      klass.header_class.from_header(img.header),
                      extra=img.extra.copy())
@@ -640,5 +640,4 @@ 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())
+    return img.from_image(img, data)