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henrydingliu merged 5 commits into from
Aug 14, 2026
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docs: add Triangle arithmetic examples (#704) #1213

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d6cf65f
docs: add Triangle arithmetic doctest examples (#704)
EKtheSage Aug 13, 2026
5dc1bf7
Move Triangle construction in arithmetic examples from testsetup into…
EKtheSage Aug 13, 2026
ef001ef
Fix E721/E722/F841 in TriangleDunders and align the autosummary templ…
EKtheSage Aug 14, 2026
8c8fd18
Merge main and keep the dunders.py ruff ignore dropped.
EKtheSage Aug 14, 2026
ccf54c0
Normalize whitespace in arithmetic doctest outputs.
EKtheSage Aug 14, 2026
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140 changes: 137 additions & 3 deletions chainladder/core/dunders.py
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Original file line number Diff line number Diff line change
Expand Up @@ -101,7 +101,7 @@ def _prep_index(self, x, y):
x = x.sort_index()
try:
y = y.loc[x.index]
except:
except Exception:
x = x.groupby(list(common))
y = y.groupby(list(common))
return x, y
Expand Down Expand Up @@ -206,7 +206,7 @@ def _prep_origin_development(self, obj, other):
other_arr.shape = (other.shape[0], other.shape[1], len(odims), len(ddims))
obj_arr.shape = (self.shape[0], self.shape[1], len(odims), len(ddims))
obj.odims = np.array(odims.index)
if type(obj.ddims) == pd.DatetimeIndex:
if isinstance(obj.ddims, pd.DatetimeIndex):
obj.ddims = pd.DatetimeIndex(ddims.index)
else:
obj.ddims = np.array(ddims.index)
Expand Down Expand Up @@ -247,6 +247,38 @@ def _arithmetic_mapper(self, obj, other, f):
return concat(c, 0).sort_index()

def __add__(self, other):
"""Element-wise addition.

Examples
--------
Adding a scalar shifts every observed cell.

.. testsetup::

import chainladder as cl

.. testcode::

tri = cl.Triangle(

@henrydingliu henrydingliu Aug 13, 2026

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should tri be in testcode instead?

@EKtheSage EKtheSage Aug 13, 2026

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Moved. testsetup is only import chainladder as cl; the Triangle is built in testcode.

data={
'origin': [1985, 1985, 1986],
'development': [1985, 1986, 1986],
'paid': [100, 150, 80],
},
origin='origin',
development='development',
columns=['paid'],
cumulative=True,
)
print(tri + 10)

.. testoutput::
:options: +NORMALIZE_WHITESPACE

12 24
1985 110.0 160.0
1986 90.0 NaN
"""
obj, other = self._validate_arithmetic(other)
if isinstance(obj, TriangleGroupBy):
def f(k, self, obj, other):
Expand All @@ -262,6 +294,36 @@ def __radd__(self, other):
return self if other == 0 else self.__add__(other)

def __sub__(self, other):
"""Element-wise subtraction.

Examples
--------
.. testsetup::

import chainladder as cl

.. testcode::

tri = cl.Triangle(
data={
'origin': [1985, 1985, 1986],
'development': [1985, 1986, 1986],
'paid': [100, 150, 80],
},
origin='origin',
development='development',
columns=['paid'],
cumulative=True,
)
print(tri - 10)

.. testoutput::
:options: +NORMALIZE_WHITESPACE

12 24
1985 90.0 140.0
1986 70.0 NaN
"""
obj, other = self._validate_arithmetic(other)
if isinstance(obj, TriangleGroupBy):
def f(k, self, obj, other):
Expand Down Expand Up @@ -306,14 +368,43 @@ def __abs__(self):
return obj

def __mul__(self, other):
"""Element-wise multiplication.

Examples
--------
.. testsetup::

import chainladder as cl

.. testcode::

tri = cl.Triangle(
data={
'origin': [1985, 1985, 1986],
'development': [1985, 1986, 1986],
'paid': [100, 150, 80],
},
origin='origin',
development='development',
columns=['paid'],
cumulative=True,
)
print(tri * 2)

.. testoutput::
:options: +NORMALIZE_WHITESPACE

12 24
1985 200.0 300.0
1986 160.0 NaN
"""
obj, other = self._validate_arithmetic(other)
if isinstance(obj, TriangleGroupBy):
def f(k, self, obj, other):
return (self._slice_or_nan(obj, other, k) *
self._slice_or_nan(other, obj, k))
obj = self._arithmetic_mapper(obj, other, f)
else:
xp = obj.get_array_module()
obj.values = obj.values * other
return obj

Expand Down Expand Up @@ -347,6 +438,49 @@ def __truediv__(self, other: Any):

other: Any
The thing that divides the triangle.

Examples
--------
Dividing by a scalar scales the triangle. Dividing two columns is the
usual way to form a ratio triangle, such as paid-to-incurred.

.. testsetup::

import chainladder as cl

.. testcode::

tri = cl.Triangle(
data={
'origin': [1985, 1985, 1986],
'development': [1985, 1986, 1986],
'paid': [100, 150, 80],
'incurred': [120, 160, 100],
},
origin='origin',
development='development',
columns=['paid', 'incurred'],
cumulative=True,
)
print(tri['paid'] / 2)

.. testoutput::
:options: +NORMALIZE_WHITESPACE

12 24
1985 50.0 75.0
1986 40.0 NaN

.. testcode::

print(tri['paid'] / tri['incurred'])

.. testoutput::
:options: +NORMALIZE_WHITESPACE

12 24
1985 0.833333 0.9375
1986 0.800000 NaN
"""
obj, other = self._validate_arithmetic(other)
if isinstance(obj, TriangleGroupBy):
Expand Down
6 changes: 5 additions & 1 deletion docs/_templates/autosummary/class_inherited.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,12 @@

.. currentmodule:: {{ module }}

{% set documented_attrs = ['loc', 'iloc', 'at', 'iat', 'shape', 'empty', 'dimensionality', 'nan_triangle'] %}
Comment thread
henrydingliu marked this conversation as resolved.
{% set hidden_attrs = attributes | reject('in', documented_attrs) | list %}

.. autoclass:: {{ objname }}
:members:
:inherited-members:
:undoc-members:
:exclude-members: set_fit_request, set_predict_request, set_score_request, set_transform_request, {{ attributes | join(', ') }}
:special-members: __add__, __sub__, __mul__, __truediv__
:exclude-members: set_fit_request, set_predict_request, set_score_request, set_transform_request{% if hidden_attrs %}, {{ hidden_attrs | join(', ') }}{% endif %}
1 change: 0 additions & 1 deletion pyproject.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -125,7 +125,6 @@ select = ["E2", "E4", "E7", "E9", "F"]
"chainladder/core/common.py" = ["F401"]
"chainladder/core/correlation.py" = ["E741"]
"chainladder/core/display.py" = ["E203", "E252"]
"chainladder/core/dunders.py" = ["E721", "E722", "F841"]
"chainladder/core/pandas.py" = ["E231", "E251", "E261", "E275", "E721", "F841"]
"chainladder/core/slice.py" = ["E225", "E712", "E721", "E741"]
"chainladder/core/tests/rtest_correlation.py" = ["E266", "E722", "F821"]
Expand Down
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