[FEAT] Fill method + Chapter 16 data

chainladder/core/tests/test_triangle.py

@@ -3304,3 +3304,22 @@ def test_fit_and_predict_on_single_origin(raa: Triangle, atol) -> None:
     np.testing.assert_allclose(
         predicted.ultimate_.values.flatten(), [expected], atol=atol
     )
+
+
+def test_fill(clrd: Triangle) -> None:
+    """
+    ``Fill`` method works as intended
+    """
+    fill_tri = clrd.iloc[2:4, 4:6].fill(100)
+    assert np.nansum(fill_tri.values) == 100 * 11 * 10 / 2 * 2 * 2
+    assert np.nanmax(fill_tri.values) == 100
+    assert np.nanmin(fill_tri.values) == 100
+
+
+def test_full_fill(raa: Triangle) -> None:
+    """
+    ``Fill`` method works as intended on full triangle
+    """
+    full_tri = cl.Chainladder().fit(raa).full_triangle_
+    fill_full_tri = full_tri.fill(200)
+    assert np.all(fill_full_tri.values == np.broadcast_to([200], (1, 1, 10, 12)))

chainladder/core/triangle.py

@@ -2357,3 +2357,28 @@ def reindex(self, columns=None, fill_value=np.nan):
             if column not in obj.columns:
                 obj[column] = fill_value
         return obj
+
+    def fill(self, value: float = 1.0, inplace: bool = False) -> Triangle:
+        """
+        Fill the Triangle with a scalar value
+
+        Parameters
+        ----------
+        value : float, default 1.0
+            All valid elements will be assigned this value
+        inplace : bool, default False
+            Whether to mutate the existing Triangle instance or return a new
+            one.
+
+        Returns
+        -------
+        Triangle
+        """
+        if inplace:
+            xp = self.get_array_module()
+            new_value = self.nan_triangle[None, None, ...].astype(np.float64)
+            self.values = xp.broadcast_to(new_value * value, self.shape).copy()
+            return self
+        else:
+            obj = self.copy()
+            return obj.fill(value, True)

chainladder/utils/data/friedland_autoprop.csv

@@ -30,9 +30,9 @@ Accident Year,Calendar Year,Reported ALAE,Paid ALAE,Reported Claims,Paid Claims
 2000,2007,862,860,116825,116807
 2000,2008,862,861,116472,116807
 2001,2001,629,480,129430,91475
-2001,2002,894,802,139925,113761
+2001,2002,894,802,139925,133761
 2001,2003,943,882,138161,136143
-2001,2004,982,836,137395,136552
+2001,2004,982,936,137395,136552
 2001,2005,997,975,137269,136818
 2001,2006,1002,987,137033,136838
 2001,2007,1003,995,136998,136960