Zip with next

CHANGELOG.md

@@ -2,13 +2,18 @@
 
 ## Release 1.6
 
+- Added [parametrize](https://pypi.org/project/parametrize/) for parameterized unit tests
 - Fixed tests failing (to find test files) when running from the IDE or the terminal when not in the right directory
 - Added Python version to GitHub Action workflow job steps and set Black to show required formatting changes
 - Upgraded pre-commit hooks (pre-commit-hooks to `v5.0.0` and ruff-pre-commit to `v0.6.0`)
 - Added [run-test.sh](run-tests.sh) script that runs all checks on code
 - Added support for Python 3.12 and 3.13 by upgrading Pylint and disabling/fixing Pylint errors
 - Corrected and improved language consistency in [readme](README.md) and `CHANGELOG.md`
 
+### New Features
+
+- Implemented `zip_with_next` function
+
 ## Release 1.5
 
 ## Release 1.4

README.md

@@ -366,6 +366,7 @@ complete documentation reference
 | `tails()`                                                                 | Returns consecutive tails of sequence                                                                                                                                                          | transformation |
 | `zip(other)`                                                              | Zips the sequence with `other`                                                                                                                                                                 | transformation |
 | `zip_with_index(start=0)`                                                 | Zips the sequence with the index starting at `start` on the right side                                                                                                                         | transformation |
+| `zip_with_next()`                                                         | Zips the sequence minus last element with itself minus first element, resulting in adjacent elements paired with each other                                                                    | transformation |
 | `enumerate(start=0)`                                                      | Zips the sequence with the index starting at `start` on the left side                                                                                                                          | transformation |
 | `cartesian(*iterables, repeat=1)`                                         | Returns cartesian product from itertools.product                                                                                                                                               | transformation |
 | `inner_join(other)`                                                       | Returns inner join of sequence with `other`. Must be a sequence of `(key, value)` pairs                                                                                                        | transformation |

functional/pipeline.py

@@ -1394,6 +1394,18 @@ def zip_with_index(self, start: int = 0) -> Sequence[tuple[_T_co, int]]:
         """
         return self._transform(transformations.zip_with_index_t(start))
 
+    def zip_with_next(self) -> Sequence[tuple[_T_co, _T_co]]:
+        """
+        Zips this sequence minus last element with itself minus first element,
+        resulting in sequence of each element paired with the next.
+
+        >>> seq([1, 2, 3, 4]).zip_with_next()
+        [(1, 2), (2, 3), (3, 4)]
+
+        :return: sequence of adjacent elements paired
+        """
+        return self._transform(transformations.zip_with_next_t())
+
     def enumerate(self, start: int = 0) -> Sequence[tuple[int, _T_co]]:
         """
         Uses python enumerate to to zip the sequence with indexes starting at start.

functional/test/test_functional.py

@@ -8,6 +8,8 @@
 from functional.transformations import name
 from functional import seq, pseq
 
+from parametrize import parametrize  # type: ignore
+
 Data = namedtuple("Data", "x y")
 
 
@@ -831,6 +833,19 @@ def test_zip_with_index(self):
         self.assertIteratorEqual(result, e)
         self.assert_type(result)
 
+    @parametrize(
+        "sequence,expected",
+        [
+            ([1, 2, 3, 4], [(1, 2), (2, 3), (3, 4)]),
+            ([i for i in range(100)], [(i, i + 1) for i in range(100 - 1)]),
+            ([], []),
+        ],
+    )
+    def test_zip_with_next(self, sequence, expected):
+        result = self.seq(sequence).zip_with_next()
+        self.assertIteratorEqual(result, expected)
+        self.assert_type(result)
+
     def test_to_list(self):
         l = [1, 2, 3, "abc", {1: 2}, {1, 2, 3}]
         result = self.seq(l).to_list()

functional/test/test_type.py

@@ -174,6 +174,10 @@ def type_checking() -> None:
             ["a", "b", "c"]
         ).zip_with_index()
 
+        t_zip_with_next: Sequence[tuple[str, str]] = seq(
+            ["a", "b", "c"]
+        ).zip_with_next()
+
         t_enumerate: Sequence[tuple[int, str]] = seq(["a", "b", "c"]).enumerate(start=1)
 
         # t_inner_join: Sequence[tuple[str, Sequence[int]]] = seq([('a', 1), ('b', 2), ('c', 3)]).inner_join([('a', 2), ('c', 5)])

functional/transformations.py

@@ -307,6 +307,16 @@ def zip_with_index_t(start):
     )
 
 
+def zip_with_next_t():
+    """
+    Transformation for Sequence.zip_with_next
+    :return: transformation
+    """
+    return Transformation(
+        "zip_with_next", lambda sequence: zip(sequence, sequence[1:]), None
+    )
+
+
 def enumerate_t(start):
     """
     Transformation for Sequence.enumerate

pyproject.toml

@@ -39,6 +39,7 @@ all = ["pandas"]
 
 [tool.poetry.group.dev.dependencies]
 black = "^23.1"
+parametrize = "^0.1.1"
 pytest = "^7.3.1"
 pylint = "^3.3.3"
 pytest-cov = "^4.0.0"