Feature: Expr and GenExpr support numpy unary func like `np.sin` #1170

Zeroto521 · 2026-01-22T10:45:12Z

Expr and GenExpr support numpy unary functions like np.sin.

Now we can do this

In [8]: x = m.addVar(name='x')

In [9]: np.sin(x)
Out[9]: sin(sum(0.0,prod(1.0,x)))

In [10]: np.cos([x, y])
Out[10]: [cos(sum(0.0,prod(1.0,x))) sin(cos(0.0,prod(1.0,y)))]

Before this, we couldn't

In [8]: x = m.addVar(name='x')

In [9]: np.sin(x)
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
AttributeError: 'pyscipopt.scip.Variable' object has no attribute 'sin'

The above exception was the direct cause of the following exception:

TypeError                                 Traceback (most recent call last)
Cell In[9], line 1
----> 1 np.sin(x)

TypeError: loop of ufunc does not support argument 0 of type pyscipopt.scip.Variable which has no callable sin method

In [12]: np.cos([x, y])
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
AttributeError: 'pyscipopt.scip.Variable' object has no attribute 'cos'

The above exception was the direct cause of the following exception:

TypeError                                 Traceback (most recent call last)
Cell In[12], line 1
----> 1 np.cos([x, y])

TypeError: loop of ufunc does not support argument 0 of type pyscipopt.scip.Variable which has no callable cos method

Introduced the ExprLike base class with __array_ufunc__ to enable numpy universal function (ufunc) support for Expr and GenExpr. Replaced standalone exp, log, sqrt, sin, and cos functions with numpy equivalents and mapped them for ufunc dispatch. This change improves interoperability with numpy and simplifies the codebase.

Added a new ExprLike base class and made Expr inherit from it. This refactoring prepares the codebase for future extensions or polymorphism involving expression-like objects.

Corrects the method call to use the first argument in the unary ufunc mapping, ensuring the correct object is used when applying numpy universal functions.

Introduces tests for unary operations such as abs, sin, and sqrt, including their numpy equivalents, to ensure correct string representations and compatibility with numpy functions.

Zeroto521 · 2026-01-22T10:49:06Z

src/pyscipopt/expr.pxi

        return expr

+
+cdef class ExprLike:


ExprLike is the base class and also a duck type.
It defines the behavior, and its subclass defines the data.
I will use ExprLike to split Variable and Expr in the future.

Added a missing colon to the ExprLike class definition in scip.pxd to conform with Python/Cython syntax.

Copilot

Pull request overview

This PR adds support for NumPy unary functions (np.sin, np.cos, np.sqrt, np.exp, np.log, np.absolute) to work with Expr and GenExpr objects by implementing the __array_ufunc__ protocol.

Changes:

Introduces a new ExprLike base class that implements __array_ufunc__ and unary operation methods
Makes Expr and GenExpr inherit from ExprLike to support NumPy ufuncs
Replaces custom function implementations with NumPy function aliases

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

File	Description
src/pyscipopt/scip.pxd	Adds `ExprLike` base class declaration and updates `Expr` inheritance hierarchy
src/pyscipopt/expr.pxi	Implements `ExprLike` with `__array_ufunc__` support, consolidates unary methods, aliases functions to NumPy equivalents
tests/test_expr.py	Adds test coverage for both custom functions and NumPy ufuncs with single expressions and arrays
CHANGELOG.md	Documents the new NumPy unary function support feature

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src/pyscipopt/expr.pxi

tests/test_expr.py

src/pyscipopt/scip.pxd

Updated test assertions in test_unary to expect variable names 'x', 'y', and 'z' instead of 'x1'. This aligns the tests with the current string representation of expressions.

Updated the expected string in test_unary to match the correct output format by removing commas between list elements.

Corrected the expected string in test_unary to use 'sin' instead of 'abs' for the sin([x, y, z]) test case.

Introduces a cpdef _evaluate method to the Constant class, returning the constant's value. This provides a consistent evaluation interface for expressions.

Removes the NotImplementedError expectation when raising genexpr to sqrt(2) and instead asserts the result is a GenExpr. Adds a new test to expect TypeError when raising to sqrt('2').

The test_unary function was moved and modified to test unary operations on lists containing two variables (x, y) instead of three (x, y, z). This streamlines the tests and aligns them with the current requirements.

Introduced a new ExprLike base class to encapsulate common mathematical methods such as __abs__, exp, log, sqrt, sin, and cos. Updated Expr and GenExpr to inherit from ExprLike, reducing code duplication and improving maintainability.

Zeroto521 · 2026-01-23T05:16:55Z

tests/test_expr.py

    assert isinstance(1/x + genexpr, GenExpr)
    assert isinstance(1/x**1.5 - genexpr, GenExpr)
    assert isinstance(y/x - exp(genexpr), GenExpr)
-    # sqrt(2) is not a constant expression and


pyscipopt.sqrt(2) = np.sqrt(2). It's a constant now, not a Constant(GenExpr)

Introduces the __array_ufunc__ method to the ExprLike class in the type stubs, enabling better compatibility with NumPy ufuncs.

…nto expr/unary

codecov · 2026-01-23T05:24:54Z

Codecov Report

❌ Patch coverage is 31.03448% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.50%. Comparing base (a82bf15) to head (857c969).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
src/pyscipopt/expr.pxi	31.03%	20 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1170      +/-   ##
==========================================
- Coverage   55.87%   55.50%   -0.37%     
==========================================
  Files          25       25              
  Lines        5502     5495       -7     
==========================================
- Hits         3074     3050      -24     
- Misses       2428     2445      +17

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Changed 'import numpy' to 'import numpy as np' and updated type annotations to use 'np.ndarray' instead of 'numpy.ndarray' in the scip.pyi stub file. Also added UNARY_MAPPER as a Dict[np.ufunc, str].

Replaces 'Incomplete' type hints with more specific types (np.ufunc and str) for the __array_ufunc__ methods in ExprLike, MatrixExpr, and MatrixExprCons classes to improve type accuracy.

Reordered the declarations of math functions and added missing entries for log, sin, and sqrt in the scip.pyi stub file to improve completeness and maintain consistency.

Moved the Operator type annotation below PATCH to maintain consistent ordering of variable declarations in the scip.pyi file.

The @disjoint_base decorator was removed from the ExprLike class in the type stub. This may reflect a change in the class hierarchy or decorator usage.

Zeroto521 · 2026-01-23T05:34:39Z

src/pyscipopt/scip.pyi

+log: Incomplete
+sin: Incomplete
+cos: Incomplete
+sqrt: Incomplete


put them together

Zeroto521 · 2026-01-23T06:58:25Z

src/pyscipopt/expr.pxi

-def cos(expr):
-    """returns expression with cos-function"""
-    if isinstance(expr, MatrixExpr):   
-        unary_exprs = np.empty(shape=expr.shape, dtype=object)
-        for idx in np.ndindex(expr.shape):
-            unary_exprs[idx] = UnaryExpr(Operator.cos, buildGenExprObj(expr[idx]))
-        return unary_exprs.view(MatrixGenExpr)
-    else:
-        return UnaryExpr(Operator.cos, buildGenExprObj(expr))


Before:

number: cos(2) will return a UnaryExpr to wrap 2.

np.ndarray(..., dtype=np.number): can't handle this.

Now:

number: cos(2) will return constant cos(2)=-0.416. Both Expr and GenExpr can handle numbers.

np.ndarray(..., dtype=np.number): return np.ndarray(..., dtype=np.number).

Replaces numpy function references in UNARY_MAPPER with local aliases (exp, log, sqrt, sin, cos) to ensure correct mapping and avoid issues with numpy function identity.

Replaces the use of Dict from typing with the built-in dict for the UNARY_MAPPER type annotation. This modernizes the type hint and removes an unused import.

Deleted the UNARY_MAPPER dictionary from scip.pyi as it is no longer needed or used in the type stub.

Zeroto521 added 6 commits January 21, 2026 18:29

Introduce ExprLike base class for expressions

4d911c1

Added a new ExprLike base class and made Expr inherit from it. This refactoring prepares the codebase for future extensions or polymorphism involving expression-like objects.

Fix unary ufunc mapping in ExprLike class

b119224

Corrects the method call to use the first argument in the unary ufunc mapping, ensuring the correct object is used when applying numpy universal functions.

Add tests for unary operations and numpy compatibility

4a65d98

Introduces tests for unary operations such as abs, sin, and sqrt, including their numpy equivalents, to ensure correct string representations and compatibility with numpy functions.

Merge branch 'master' into expr/unary

2d8945f

Update CHANGELOG.md

01658f4

Copilot AI review requested due to automatic review settings January 22, 2026 10:45

Copilot started reviewing on behalf of Zeroto521 January 22, 2026 10:45 View session

Zeroto521 commented Jan 22, 2026

View reviewed changes

Add colon to ExprLike class definition

f0aacb6

Added a missing colon to the ExprLike class definition in scip.pxd to conform with Python/Cython syntax.

Zeroto521 mentioned this pull request Jan 22, 2026

Feature: Merge Expr and GenExpr #1074

Open

Copilot AI reviewed Jan 22, 2026

View reviewed changes

Zeroto521 added 9 commits January 22, 2026 18:59

Fix test expectations for variable names in unary ops

7e78cac

Updated test assertions in test_unary to expect variable names 'x', 'y', and 'z' instead of 'x1'. This aligns the tests with the current string representation of expressions.

Fix expected output format in test_unary

196f43a

Updated the expected string in test_unary to match the correct output format by removing commas between list elements.

Fix expected output for sin function in test_unary

6dd2c93

Corrected the expected string in test_unary to use 'sin' instead of 'abs' for the sin([x, y, z]) test case.

Merge branch 'master' into expr/unary

ee4c6f6

Add _evaluate method to Constant class

e76b0d6

Introduces a cpdef _evaluate method to the Constant class, returning the constant's value. This provides a consistent evaluation interface for expressions.

Update genexpr power tests for sqrt handling

06b4df4

Removes the NotImplementedError expectation when raising genexpr to sqrt(2) and instead asserts the result is a GenExpr. Adds a new test to expect TypeError when raising to sqrt('2').

Update test_unary to use two variables instead of three

a76ef44

The test_unary function was moved and modified to test unary operations on lists containing two variables (x, y) instead of three (x, y, z). This streamlines the tests and aligns them with the current requirements.

Refactor expression classes with ExprLike base

5611d52

Introduced a new ExprLike base class to encapsulate common mathematical methods such as __abs__, exp, log, sqrt, sin, and cos. Updated Expr and GenExpr to inherit from ExprLike, reducing code duplication and improving maintainability.

Merge branch 'master' into expr/unary

3402b32

Zeroto521 commented Jan 23, 2026

View reviewed changes

Zeroto521 added 2 commits January 23, 2026 13:19

Add __array_ufunc__ to ExprLike type stub

925cb43

Introduces the __array_ufunc__ method to the ExprLike class in the type stubs, enabling better compatibility with NumPy ufuncs.

Merge branch 'expr/unary' of https://github.com/Zeroto521/PySCIPOpt i…

857c969

…nto expr/unary

Zeroto521 added 5 commits January 23, 2026 13:27

Update numpy import and type annotations in stubs

c94177c

Changed 'import numpy' to 'import numpy as np' and updated type annotations to use 'np.ndarray' instead of 'numpy.ndarray' in the scip.pyi stub file. Also added UNARY_MAPPER as a Dict[np.ufunc, str].

Update __array_ufunc__ type hints to use np.ufunc and str

588cba4

Replaces 'Incomplete' type hints with more specific types (np.ufunc and str) for the __array_ufunc__ methods in ExprLike, MatrixExpr, and MatrixExprCons classes to improve type accuracy.

Reorder and add math functions in scip.pyi

cd642f9

Reordered the declarations of math functions and added missing entries for log, sin, and sqrt in the scip.pyi stub file to improve completeness and maintain consistency.

Reorder Operator and PATCH declarations in scip.pyi

f8e6132

Moved the Operator type annotation below PATCH to maintain consistent ordering of variable declarations in the scip.pyi file.

Remove @disjoint_base decorator from ExprLike

940fd93

The @disjoint_base decorator was removed from the ExprLike class in the type stub. This may reflect a change in the class hierarchy or decorator usage.

Zeroto521 commented Jan 23, 2026

View reviewed changes

Zeroto521 added 3 commits January 23, 2026 15:05

Fix UNARY_MAPPER to use local math function references

900fdc3

Replaces numpy function references in UNARY_MAPPER with local aliases (exp, log, sqrt, sin, cos) to ensure correct mapping and avoid issues with numpy function identity.

Update typing for UNARY_MAPPER in scip.pyi

c85be94

Replaces the use of Dict from typing with the built-in dict for the UNARY_MAPPER type annotation. This modernizes the type hint and removes an unused import.

Remove unused UNARY_MAPPER from type stub

4f6058a

Deleted the UNARY_MAPPER dictionary from scip.pyi as it is no longer needed or used in the type stub.

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Feature: Expr and GenExpr support numpy unary func like `np.sin` #1170

Feature: Expr and GenExpr support numpy unary func like `np.sin` #1170

Zeroto521 commented Jan 22, 2026 •

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Feature: Expr and GenExpr support numpy unary func like `np.sin` #1170

Feature: Expr and GenExpr support numpy unary func like `np.sin` #1170

Zeroto521 commented Jan 22, 2026 •

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