Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Duplicate Variables Bandaid #397

Open
wants to merge 2 commits into
base: master
Choose a base branch
from
Open

Duplicate Variables Bandaid #397

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
e76f1e0
test: add indentical variable constraints
ItsNiklas Nov 11, 2024
ca7f8d9
entities: Avoid voiding coefficients in LinExpr creation from Var ove…
ItsNiklas Nov 11, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
15 changes: 15 additions & 0 deletions mip/entities.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,9 @@ class LinExpr:
a = 10*x1 + 7*x4
print(a.x)

.. warning::
Do not pass identical objects in the ``variables`` argument when constructing
a LinExpr manually.
"""

__slots__ = ["__const", "__expr", "__sense"]
Expand Down Expand Up @@ -542,6 +545,8 @@ def __add__(
self, other: Union["mip.Var", LinExpr, numbers.Real]
) -> Union["mip.Var", LinExpr]:
if isinstance(other, Var):
if id(self) == id(other):
return LinExpr([self], [2])
return LinExpr([self, other], [1, 1])
if isinstance(other, LinExpr):
return other.__add__(self)
Expand All @@ -561,6 +566,8 @@ def __sub__(
self, other: Union["mip.Var", LinExpr, numbers.Real]
) -> Union["mip.Var", LinExpr]:
if isinstance(other, Var):
if id(self) == id(other):
return LinExpr([self], [0])
return LinExpr([self, other], [1, -1])
if isinstance(other, LinExpr):
return (-other).__add__(self)
Expand All @@ -575,6 +582,8 @@ def __rsub__(
self, other: Union["mip.Var", LinExpr, numbers.Real]
) -> Union["mip.Var", LinExpr]:
if isinstance(other, Var):
if id(self) == id(other):
return LinExpr([self], [0])
return LinExpr([self, other], [-1, 1])
if isinstance(other, LinExpr):
return other.__sub__(self)
Expand Down Expand Up @@ -603,6 +612,8 @@ def __neg__(self) -> LinExpr:

def __eq__(self, other) -> LinExpr:
if isinstance(other, Var):
if id(self) == id(other):
return LinExpr([self], [0], sense="=")
return LinExpr([self, other], [1, -1], sense="=")
if isinstance(other, LinExpr):
return LinExpr([self], [1]) == other
Expand All @@ -613,6 +624,8 @@ def __eq__(self, other) -> LinExpr:

def __le__(self, other: Union["mip.Var", LinExpr, numbers.Real]) -> LinExpr:
if isinstance(other, Var):
if id(self) == id(other):
return LinExpr([self], [0], sense="<")
return LinExpr([self, other], [1, -1], sense="<")
if isinstance(other, LinExpr):
return LinExpr([self], [1]) <= other
Expand All @@ -623,6 +636,8 @@ def __le__(self, other: Union["mip.Var", LinExpr, numbers.Real]) -> LinExpr:

def __ge__(self, other: Union["mip.Var", LinExpr, numbers.Real]) -> LinExpr:
if isinstance(other, Var):
if id(self) == id(other):
return LinExpr([self], [0], sense=">")
return LinExpr([self, other], [1, -1], sense=">")
if isinstance(other, LinExpr):
return LinExpr([self], [1]) >= other
Expand Down
23 changes: 23 additions & 0 deletions test/mip_test.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
from os import environ

import networkx as nx
from mip.entities import LinExpr
import mip.gurobi
import mip.highs
from mip import Model, xsum, OptimizationStatus, MAXIMIZE, BINARY, INTEGER
Expand Down Expand Up @@ -578,6 +579,28 @@ def test_obj_const2(self, solver: str):
assert model.objective_const == 1


@skip_on(NotImplementedError)
@pytest.mark.parametrize("solver", SOLVERS)
@pytest.mark.parametrize("constraint, lb, ub", [
(lambda x: x + x >= 3, 1, 2),
(lambda x: x - x >= 0, 1, 2),
(lambda x: x == x, 1, 2),
(lambda x: x >= x, 1, 2),
(lambda x: x <= x, -2, -1),
# (lambda x: LinExpr([x, x, x], [2, -1, -1], sense="="), 1, 2),
])
def test_identical_vars(solver: str, constraint, lb, ub):
"""Try if constraints are correctly added when variables are identical"""
m = Model(solver_name=solver)
x = m.add_var(name="x", lb=lb, ub=ub, obj=1)

m.add_constr(constraint(x))

m.optimize()
assert m.status == OptimizationStatus.OPTIMAL
assert lb - TOL <= x.x <= ub + TOL


@skip_on(NotImplementedError)
@pytest.mark.parametrize("val", range(1, 4))
@pytest.mark.parametrize("solver", SOLVERS)
Expand Down