OMMX adaptor for Python-MIP

This package provides an adaptor for the Python-MIP from/to OMMX

Python-MIP as a solver in OMMX toolchain

sequenceDiagram
    participant U as User
    participant A as Adapter
    participant P as Python-MIP
    U->>A: ommx.v1.Instance
    A->>U: Python-MIP model
    U->>P: Python-MIP model and Parameters for Python-MIP;
    P->>P: Solve with CBC, Gurobi, or other solvers
    P->>U: Optimized model
    U->>A: Optimized model and ommx.v1.Instance
    A->>U: ommx:SolutionList

Python-MIP as a user interface to create OMMX instance

sequenceDiagram
    participant U as User
    participant A as Adapter
    participant O as Other OMMX toolchain
    U->>A: Python-MIP model
    A->>U: ommx.v1.Instance
    U->>O: ommx.v1.Instance and Parameters for other solver
    O->>O: Solve the instance with other solver using other adapter
    O->>U: ommx.v1.Solution

Usage

ommx-python-mip-adapter can be installed from PyPI as follows:

pip install ommx-python-mip-adapter

Python-MIP can be used through ommx-python-mip-adapter by using the following:

import ommx_python_mip_adapter as adapter
from ommx.v1.decision_variables_pb2 import DecisionVariable, Bound
from ommx.v1.instance_pb2 import Instance
from ommx.v1.function_pb2 import Function
from ommx.v1.linear_pb2 import Linear
from ommx.v1.solution_pb2 import SolutionList

ommx_instance = Instance(
    decision_variables=[
        DecisionVariable(
            id=1,
            kind=DecisionVariable.KIND_INTEGER,
            bound=Bound(lower=0, upper=5),
        ),
    ],
    objective=Function(
        linear=Linear(
            terms=[Linear.Term(id=1, coefficient=1)]
        ),
    ),
)
ommx_instance_bytes = ommx_instance.SerializeToString()

# Convert from `ommx.v1.Instance` to `mip.Model`
model = adapter.instance_to_model(ommx_instance_bytes)
model.optimize()
# Create `ommx.v1.SolutionList` from Optimized `mip.Model`
ommx_solutions_bytes = adapter.model_to_solution(
    model, ommx_instance_bytes
)

print(SolutionList.FromString(ommx_solutions_bytes))

You can get ommx.v1.Instance from a Python-MIP model as the following:

import mip
import ommx_python_mip_adapter as adapter
from ommx.v1.instance_pb2 import Instance

model = mip.Model()
x1=model.add_var(name="1", var_type=mip.INTEGER, lb=0, ub=5)
x2=model.add_var(name="2", var_type=mip.CONTINUOUS, lb=0, ub=5)
model.objective = - x1 - 2 * x2
model.add_constr(x1 + x2 - 6 <= 0)

ommx_instance_bytes = adapter.model_to_instance(model)

print(Instance.FromString(ommx_instance_bytes))

Reference

• OMMX-Python-MIP-Adapter API Reference