TEST: Check world direction of encoding remains consistent

Author: effigies

nibabel/tests/test_nifti1.py

@@ -28,6 +28,7 @@
 from nibabel.spatialimages import HeaderDataError
 from nibabel.tmpdirs import InTemporaryDirectory
 from ..freesurfer import load as mghload
+from ..orientations import axcodes2ornt
 
 from .test_arraywriters import rt_err_estimate, IUINT_TYPES
 from .test_helpers import bytesio_filemap, bytesio_round_trip
@@ -1403,6 +1404,40 @@ def test_rt_bias(self):
                 bias_thresh = np.max([max_miss / np.sqrt(count), eps])
                 assert_true(np.abs(bias) < bias_thresh)
 
+    def test_reoriented_dim_info(self):
+        # Check that dim_info is reoriented correctly
+        arr = np.arange(24).reshape((2, 3, 4))
+        # Start as RAS
+        aff = np.diag([2, 3, 4, 1])
+        simg = self.single_class(arr, aff)
+        axcodes = ('RAS', 'RPS',  # Include a flip
+                   'RSA', 'RSP',  # Include a flip + reorientation
+                   'ARS',
+                   'ASR',
+                   'SRA',
+                   'SAR')
+        for freq, phas, slic in ((0, 1, 2),
+                                 (0, 2, 1),
+                                 (None, None, None),
+                                 (0, 2, None),
+                                 (0, None, None),
+                                 (None, 2, 1),
+                                 (None, None, 1),
+                                 ):
+            simg.header.set_dim_info(freq, phas, slic)
+            fdir = 'RAS'[freq] if freq is not None else None
+            pdir = 'RAS'[phas] if phas is not None else None
+            sdir = 'RAS'[slic] if slic is not None else None
+            for axcode in axcodes:
+                ornt = axcodes2ornt(axcode)
+                rimg = simg.as_reoriented(ornt)
+                dirs = axcode.replace('P', 'A')  # Polarity doesn't matter
+                new_freq, new_phas, new_slic = rimg.header.get_dim_info()
+                new_fdir = dirs[new_freq] if new_freq is not None else None
+                new_pdir = dirs[new_phas] if new_phas is not None else None
+                new_sdir = dirs[new_slic] if new_slic is not None else None
+                assert_equal((new_fdir, new_pdir, new_sdir), (fdir, pdir, sdir))
+
 
 @runif_extra_has('slow')
 def test_large_nifti1():