From c24fe2e692c586aa5d7b887b86bef5dd65830bd5 Mon Sep 17 00:00:00 2001
From: DanRyanIrish <ryand5@tcd.ie>
Date: Mon, 13 Apr 2020 10:33:13 -0400
Subject: [PATCH] Merge pull request #251 from hayesla/ndcube_sequence_slicing

First step to simplify NDCubeSequence slicing implementation
---
 changelog/251.trivial.rst |  1 +
 ndcube/ndcube_sequence.py | 21 +++++++++++++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)
 create mode 100644 changelog/251.trivial.rst

diff --git a/changelog/251.trivial.rst b/changelog/251.trivial.rst
new file mode 100644
index 000000000..dc5e35050
--- /dev/null
+++ b/changelog/251.trivial.rst
@@ -0,0 +1 @@
+Simplify and speed up implementation of NDCubeSequence slicing.
\ No newline at end of file
diff --git a/ndcube/ndcube_sequence.py b/ndcube/ndcube_sequence.py
index 558983c6d..eb5a35d75 100644
--- a/ndcube/ndcube_sequence.py
+++ b/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):