Merge pull request #268 from DanRyanIrish/1.3.1

Cherry-pick 1.3.1 commits to 1.3 branch

changelog/251.trivial.rst

@@ -0,0 +1 @@
+Simplify and speed up implementation of NDCubeSequence slicing.

changelog/264.bugfix.rst

@@ -0,0 +1 @@
+Fix NDCollection.aligned_dimensions so it doesnt crash when components of collection are NDCubeSequences.

ndcube/ndcollection.py

@@ -94,7 +94,8 @@ def aligned_dimensions(self):
 
         """
         if self.aligned_axes is not None:
-            return self[self._first_key].dimensions[np.array(self.aligned_axes[self._first_key])]
+            return np.asanyarray(self[self._first_key].dimensions, dtype=object)[
+                    np.array(self.aligned_axes[self._first_key])]
 
     @property
     def aligned_world_axis_physical_types(self):

ndcube/ndcube_sequence.py

@@ -85,12 +85,25 @@ def cube_like_world_axis_physical_types(self):
     def __getitem__(self, item):
         if isinstance(item, numbers.Integral):
             return self.data[item]
-        elif isinstance(item, slice):
+        else:
             result = copy.deepcopy(self)
-            result.data = self.data[item]
+            if isinstance(item, slice):
+                result.data = self.data[item]
+            else:
+                if isinstance(item[0], numbers.Integral):
+                    result = result.data[item[0]][item[1:]]
+                else:
+                    item0_is_length1_slice = False
+                    if isinstance(item[0], slice):
+                        start = 0 if item[0].start is None else item[0].start
+                        stop = len(self.data) if item[0].stop is None else item[0].stop
+                        if stop - start == 1:
+                            item0_is_length1_slice = True
+                    if item0_is_length1_slice:
+                        result.data = [result.data[start][item[1:]]]
+                    else:
+                        result.data = [cube[item[1:]] for cube in result.data[item[0]]]
             return result
-        else:
-            return utils.sequence.slice_sequence(self, item)
 
     @property
     def index_as_cube(self):

ndcube/tests/test_ndcollection.py

@@ -3,6 +3,7 @@
 import pytest
 import numpy as np
 import astropy.wcs
+import astropy.units as u
 
 from ndcube import NDCube, NDCubeSequence, NDCollection
 from ndcube.tests import helpers
@@ -130,3 +131,10 @@ def test_collection_update_collecton_input():
     expected = NDCollection([("cube0", cube0), ("cube1", cube1_alt), ("cube2", cube2)],
                             aligned_axes)
     helpers.assert_collections_equal(orig_collection, expected)
+
+
+@pytest.mark.parametrize("collection, expected_aligned_dimensions", [
+    (cube_collection, [4, 5]*u.pix),
+    (seq_collection, np.array([2*u.pix, 3*u.pix, 4*u.pix, 5*u.pix], dtype=object))])
+def test_aligned_dimensions(collection, expected_aligned_dimensions):
+    assert all(collection.aligned_dimensions == expected_aligned_dimensions)