IBM Decision Optimization CPLEX Modeling for Python (DOcplex)

2.32.264 verified Fri May 01 auth: no python

DOcplex is a modeling library for mathematical optimization, providing a Python API to IBM ILOG CPLEX and CP Optimizer solvers. Current version 2.32.264 supports linear, mixed-integer, and constraint programming. Release cadence is quarterly.

pip install docplex

Common errors

error docplex.util.environment.DOcplexException: Model has no solution ↓

cause Solver failed to find a feasible solution or model is infeasible.

fix

Check model constraints for conflicts or use mdl.refine_conflict() to diagnose infeasibility.

error ImportError: cannot import name 'Model' from 'docplex' ↓

cause Incorrect import path; Model is in `docplex.mp.model`.

fix

Use from docplex.mp.model import Model instead of from docplex import Model.

error NameError: name 'IntegerVarType' is not defined ↓

cause Deprecated import removed in newer versions.

fix

Use model.integer_var() or model.binary_var() directly, not IntegerVarType.

Warnings

breaking In DOcplex 2.10+, the `CpoModel.solve()` returns a `CpoSolveResult` instead of a tuple. Code relying on tuple unpacking will break. ↓

fix Access result attributes directly (e.g., `sol.get_objective_value()`) rather than unpacking.

deprecated `docplex.mp.vartype` (e.g., `IntegerVarType`) is deprecated in favor of using `docplex.mp.model.Model.integer_var()` directly. ↓

fix Use model methods like `model.integer_var()`, `model.binary_var()`, and `model.continuous_var()` instead.

gotcha DOcplex requires a CPLEX license to solve locally (free for academic users with IBM Academic Initiative). Without a local CPLEX installation or cloud subscription, `solve()` will raise a `DOcplexException`. ↓

fix Install CPLEX (e.g., `pip install cplex`) and set up license, or use IBM Decision Optimization on Cloud (set `url` and `key` in `Model.solve()`).

Imports

Model
wrong
```
from docplex import Model
```
correct
```
from docplex.mp.model import Model
```
Model is not directly in the docplex namespace; import from docplex.mp.model.
CpoModel
wrong
```
from docplex import CpoModel
```
correct
```
from docplex.cp.model import CpoModel
```
CpoModel is not directly in the docplex namespace; import from docplex.cp.model.

Quickstart

Create a simple mixed-integer programming model, add variables and constraints, maximize objective, and solve.

from docplex.mp.model import Model

mdl = Model(name='example')
x = mdl.integer_var(name='x')
y = mdl.integer_var(name='y')
mdl.add_constraint(x + y <= 10)
mdl.maximize(x + 2*y)
solution = mdl.solve()
if solution:
    print(f'x = {x.solution_value}, y = {y.solution_value}')