TEST: Test backported reorienting function

Author: effigies

nipype/interfaces/tests/test_image.py

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+# emacs: -*- mode: python; py-indent-offset: 4; indent-tabs-mode: nil -*-
+# vi: set ft=python sts=4 ts=4 sw=4 et:
+import numpy as np
+import nibabel as nb
+import pytest
+
+from nibabel.orientations import axcodes2ornt, ornt_transform
+
+from ..image import _as_reoriented_backport, _orientations
+from ... import LooseVersion
+
+nibabel22 = LooseVersion(nb.__version__) >= LooseVersion('2.2.0')
+
+
+@pytest.mark.skipif(not nibabel22,
+                    reason="Old nibabel - can't directly compare")
+def test_reorientation_backport():
+    pixdims = ((1, 1, 1), (2, 2, 3))
+    data = np.random.normal(size=(17, 18, 19, 2))
+
+    for pixdim in pixdims:
+        # Generate a randomly rotated affine
+        angles = np.random.uniform(-np.pi, np.pi, 3) * [1, 0.5, 1]
+        rot = nb.eulerangles.euler2mat(*angles)
+        scale = np.diag(pixdim)
+        translation = np.array((17, 18, 19)) / 2
+        affine = nb.affines.from_matvec(rot.dot(scale), translation)
+
+        # Create image
+        img = nb.Nifti1Image(data, affine)
+        dim_info = {'freq': 0, 'phase': 1, 'slice': 2}
+        img.header.set_dim_info(**dim_info)
+
+        # Find a random, non-identity transform
+        targ_ornt = orig_ornt = nb.io_orientation(affine)
+        while np.array_equal(targ_ornt, orig_ornt):
+            new_code = np.random.choice(_orientations)
+            targ_ornt = axcodes2ornt(new_code)
+
+        identity = ornt_transform(orig_ornt, orig_ornt)
+        transform = ornt_transform(orig_ornt, targ_ornt)
+
+        # Identity transform returns exact image
+        assert img.as_reoriented(identity) is img
+        assert _as_reoriented_backport(img, identity) is img
+
+        reoriented_a = img.as_reoriented(transform)
+        reoriented_b = _as_reoriented_backport(img, transform)
+
+        # Reorientation changes affine and data array
+        assert not np.allclose(img.affine, reoriented_a.affine)
+        assert not (img.shape == reoriented_a.shape and
+                    np.allclose(img.get_data(), reoriented_a.get_data()))
+        assert not np.array_equal(img.header.get_dim_info(),
+                                  reoriented_a.header.get_dim_info())
+
+        # Both approaches produce equivalent images
+        assert np.allclose(reoriented_a.affine, reoriented_b.affine)
+        assert np.array_equal(reoriented_a.get_data(), reoriented_b.get_data())
+        assert np.array_equal(reoriented_a.header.get_dim_info(),
+                              reoriented_b.header.get_dim_info())