Example: mip1

This example builds a trivial MIP model, solves it, and prints the solution.

In the following sections, we will walk through the example, line by line, to understand how it achieves the desired result of optimizing the indicated model.

The example

Our example optimizes the following model:

Python interface

The complete source code for our example can be found in: 

• Online: Example mip1.py
• Distribution:  <installdir>/examples/python/mip1.py

The example begins by importing Gurobi functions and classes:

import gurobipy as gp
from gurobipy import GRB

The first line makes all Gurobi functions and classes available through a gp. prefix (e.g., gp.Model()). The second makes everything in class GRB available without a prefix (e.g., GRB.OPTIMAL). You can also start a program with from gurobipy import * to remove the need for the gp. prefix, but if your program uses multiple Python modules it is usually preferred to access each through its own prefix.

In order for these commands to succeed, the Python application needs to know how to find the Gurobi functions and classes. Recall that you have three options for installing them.

Python Matrix interface

The complete source code for our example can be found in: 

• Online: Example matrix1.py
• Distribution:  <installdir>/examples/python/matrix1.py>

The example begins by importing the Gurobi functions and classes, as well as the NumPy and SciPy packages:

import gurobipy as gp
from gurobipy import GRB
import numpy as np
import scipy.sparse as sp

Gurobi Python applications should always start with the first two lines. If you want to use the matrix interface, the last two lines are needed as well.

C interface

The complete source code for our example can be found in: 

• Online: Example mip1_c.c
• Distribution:  <installdir>/examples/c/mip1_c.c

The example begins by including a few include files. Gurobi C applications should always start by including gurobi_c.h, along with the standard C include files (stdlib.h and stdio.h).

C++ interface

The complete source code for our example can be found in: 

• Online: Example mip1_cpp.cpp
• Distribution:  <installdir>/examples/cpp/mip1_cpp.cpp

The example begins by including file gurobi_c++.h. Gurobi C++ applications should always start by including this file.

Java interface

The complete source code for our example can be found in: 

• Online: Example Mip1.java
• Distribution:  <installdir>/examples/java/Mip1.java

The example begins by importing the Gurobi classes (import gurobi.*). Gurobi Java applications should always start with this line.

.NET interface

The complete source code for our example can be found in: 

• Online: Example mip1_cs.cs
• Distribution:  <installdir>/examples/c#/mip1_cs.cs

The example begins by importing the Gurobi namespace (using Gurobi). Gurobi .NET applications should always start with this line.

MATLAB interface

The complete source code for our example can be found in: 

• Online: Example mip1.m
• Distribution:  <installdir>/examples/matlab/mip1.m

R interface

The complete source code for our example can be found in: 

• Online: Example mip1.R
• Distribution:  <installdir>/examples/R/mip.R

The example begins by importing the Gurobi package (library('gurobi')). R programs that call Gurobi must include this line.