Add helper function to generate sliding windows of length N over iterable

Function `sliding_window` copied from
https://docs.python.org/3/library/itertools.html#itertools-recipes

Author: simu

commodore/helpers.py

@@ -1,4 +1,5 @@
 import collections
+import itertools
 import json
 import shutil
 import os
@@ -228,3 +229,14 @@ def relsymlink(src: P, dest_dir: P, dest_name: Optional[str] = None):
     if link_dst.exists():
         os.remove(link_dst)
     os.symlink(link_src, link_dst)
+
+
+def sliding_window(iterable, n):
+    # sliding_window('ABCDEFG', 4) -> ABCD BCDE CDEF DEFG
+    it = iter(iterable)
+    window = collections.deque(itertools.islice(it, n), maxlen=n)
+    if len(window) == n:
+        yield tuple(window)
+    for x in it:
+        window.append(x)
+        yield tuple(window)

tests/test_helpers.py

@@ -134,3 +134,33 @@ def test_yaml_dump(tmp_path: Path, input, expected):
 )
 def test_yaml_dump_all(tmp_path: Path, input, expected):
     _test_yaml_dump_fun(helpers.yaml_dump_all, tmp_path, input, expected)
+
+
+@pytest.mark.parametrize(
+    "sequence,winsize,expected",
+    [
+        (
+            "abcd",
+            1,
+            [("a",), ("b",), ("c",), ("d",)],
+        ),
+        (
+            "abcd",
+            2,
+            [("a", "b"), ("b", "c"), ("c", "d")],
+        ),
+        (
+            "abcd",
+            4,
+            [("a", "b", "c", "d")],
+        ),
+        (
+            ["aaa", "bbb", "ccc", "ddd"],
+            2,
+            [("aaa", "bbb"), ("bbb", "ccc"), ("ccc", "ddd")],
+        ),
+    ],
+)
+def test_sliding_window(sequence, winsize, expected):
+    windows = list(helpers.sliding_window(sequence, winsize))
+    assert windows == expected