FEAT: Add validation to TrianglePandas.rename. Also add tests to ensure cascading of rename to triangle.columns_label.

chainladder/core/pandas.py

@@ -20,7 +20,11 @@
     from collections.abc import Callable
     from numpy.typing import ArrayLike
     from types import ModuleType
-    from typing import Type
+    from typing import (
+        Literal,
+        Self,
+        Type
+    )
 
 
 
@@ -308,7 +312,11 @@ def append(self, other):
 
         return concat((self, other), 0)
 
-    def rename(self, axis, value):
+    def rename(
+            self,
+            axis: Literal['index', 'columns', 'origin', 'development'] | int,
+            value: list | str
+    ) -> Self:
         """Alter axes labels.
 
         Parameters
@@ -328,12 +336,18 @@ def rename(self, axis, value):
         value = [value] if type(value) is str else value
         if axis == "index" or axis == 0:
             self.index = value
-        if axis == "columns" or axis == 1:
+        elif axis == "columns" or axis == 1:
             self.columns = value
-        if axis == "origin" or axis == 2:
+        elif axis == "origin" or axis == 2:
             self.origin = value
-        if axis == "development" or axis == 3:
+        elif axis == "development" or axis == 3:
             self.development = value
+        else:
+            raise ValueError(
+                "Invalid value provided to the 'axis' parameter. Accepted values are a string of 'index', "
+                 "'columns', 'origin', or 'development', or an integer in the interval [0, 4] specifying the"
+                 " axis to be modified."
+            )
         return self
 
     def astype(self, dtype, inplace=True):

chainladder/core/tests/test_triangle.py

@@ -89,6 +89,30 @@ def test_append(raa):
     raa.append(raa2).sum() == raa * 2
     assert raa.append(raa2).sum() == 2 * raa
 
+def test_rename_columns(genins, clrd) -> None:
+    """
+    Test the renaming of triangle columns.
+    """
+    # Scalar case - single column triangle.
+    genins.rename('columns', 'foo')
+
+    assert genins.columns.to_list() == ['foo']
+
+    # Test the cascading of rename to triangle.columns_label.
+    assert genins.columns_label == ['foo']
+
+def test_rename_exception(genins, clrd) -> None:
+    # Test incorrect axis argument - misspelling of string.
+    with pytest.raises(ValueError):
+        genins.rename('colunms', 'foo')
+
+    # Test incorrect axis integer.
+    with pytest.raises(ValueError):
+        genins.rename(4, 'foo')
+
+    # Test incorrect number of columns.
+    with pytest.raises(ValueError):
+        clrd.rename('columns', ['foo'])
 
 def test_assign_existing_col(qtr):
     out = qtr.copy()

chainladder/core/triangle.py

@@ -149,7 +149,6 @@ def __init__(
         )
 
         # Store dimension metadata.
-        self.columns_label: list = columns
         self.origin_label: list = origin
 
         # Handle any ultimate vectors in triangles separately.
@@ -401,6 +400,10 @@ def columns(self, value):
             self.vdims = np.array(self.vdims)
         self._set_slicers()
 
+    @property
+    def columns_label(self) -> list:
+        return self.columns.to_list()
+
     @property
     def origin(self):
         if self.is_pattern and len(self.odims) == 1: