From 5c54e8b62ec1b0526daf33bb34bceb3a62d04fc8 Mon Sep 17 00:00:00 2001 From: Antonio Valentino Date: Mon, 22 Dec 2025 01:34:19 +0100 Subject: [PATCH] Support nevative step in normalize_indexer --- xarray/core/indexing.py | 7 ++++--- xarray/tests/test_indexing.py | 3 ++- 2 files changed, 6 insertions(+), 4 deletions(-) --- a/xarray/core/indexing.py +++ b/xarray/core/indexing.py @@ -257,7 +257,8 @@ >>> normalize_slice(slice(0, -1), 10) slice(0, 9, 1) """ - return slice(*sl.indices(size)) + start, stop, step = sl.indices(size) + return slice(start, stop if stop >= 0 else None, step) def _expand_slice(slice_: slice, size: int) -> np.ndarray[Any, np.dtype[np.integer]]: @@ -280,14 +281,14 @@ index it with another slice to return a new slice equivalent to applying the slices sequentially """ - old_slice = normalize_slice(old_slice, size) + old_slice = slice(*old_slice.indices(size)) size_after_old_slice = len(range(old_slice.start, old_slice.stop, old_slice.step)) if size_after_old_slice == 0: # nothing left after applying first slice return slice(0) - applied_slice = normalize_slice(applied_slice, size_after_old_slice) + applied_slice = slice(*applied_slice.indices(size_after_old_slice)) start = old_slice.start + applied_slice.start * old_slice.step if start < 0: --- a/xarray/tests/test_indexing.py +++ b/xarray/tests/test_indexing.py @@ -282,10 +282,11 @@ (-1, 3, 2), (slice(None), 4, slice(0, 4, 1)), (slice(1, -3), 7, slice(1, 4, 1)), + (slice(None, None, -1), 8, slice(7, None, -1)), (np.array([-1, 3, -2]), 5, np.array([4, 3, 3])), ), ) - def normalize_indexer(self, indexer, size, expected): + def test_normalize_indexer(self, indexer, size, expected): actual = indexing.normalize_indexer(indexer, size) if isinstance(expected, np.ndarray):