BF+TEST: float affine truncation in make_xyz_image

matthew-brett · matthew-brett · commit 6fc3af4aebb2 · 2012-06-16T15:07:32.000-07:00
Satra noticed via Alexis' realign4d that image voxel sizes were being
truncated to integers during make_xyz_image.  Fix and test.
diff --git a/nipy/core/image/image_spaces.py b/nipy/core/image/image_spaces.py
@@ -369,7 +369,7 @@ def make_xyz_image(data, xyz_affine, world, metadata=None):
     world_cm = rsp.get_world_cs(world, N)
     voxel_cm = rsp.voxel_csm(N)
     if N > 3:
-        affine = np.diag((1, 1, 1) + added_zooms + (1,))
+        affine = np.diag((1., 1, 1) + added_zooms + (1,))
         affine[:3, :3] = xyz_affine[:3, :3]
         affine[:3, -1] = xyz_affine[:3, 3]
     else:
diff --git a/nipy/core/image/tests/test_image_spaces.py b/nipy/core/image/tests/test_image_spaces.py
@@ -158,3 +158,9 @@ def test_make_xyz_image():
     assert_true(is_xyz_affable(img))
     # Need at least 3 dimensions in data
     assert_raises(ValueError, make_xyz_image, np.zeros((2,3)), aff, 'mni')
+    # Check affines don't round / floor floating point
+    aff = np.diag([2.1, 3, 4, 1])
+    img = make_xyz_image(np.zeros((2, 3, 4)), aff, 'scanner')
+    assert_array_equal(img.coordmap.affine, aff)
+    img = make_xyz_image(np.zeros((2, 3, 4, 5)), aff, 'scanner')
+    assert_array_equal(img.coordmap.affine, np.diag([2.1, 3, 4, 1, 1]))
