Gurobi: Difference between revisions

  My Compute Canada username is "_______" and I am a member of the academic institution "_____________________".  This message confirms that I will only use the Compute Canada Gurobi license provided on Compute Canada systems for the purpose of non-commercial research project(s) to be published in publicly available article(s).

===Gurobi Command-Line Tools=== <!--T:5-->

  [gra800:~] module load gurobi

  [gra800:~] gurobi_cl Record=1 Threads=8 Method=2 ResultFile=p0033.sol LogFile=p0033.log $GUROBI_HOME/examples/data/p0033.mps

  gurobi> help()

where

     * https://www.gurobi.com/documentation/8.1/refman/recording_api_calls.html

===Replay API Call Recording=== <!--T:7-->

Reference: https://www.gurobi.com/documentation/8.1/refman/recording_api_calls.html

This is an example job script for an optimization model written in the [https://www.gurobi.com/documentation/8.1/refman/lp_format.html LP format].

{{File

module load gurobi

# Create environment file in current directory setting the number of threads:

echo "Threads ${SLURM_CPUS_ON_NODE:-1}" > gurobi.env

gurobi_cl ${GUROBI_HOME}/examples/data/coins.lp

}}

This is an example jobscript for a model using [https://www.gurobi.com/documentation/8.1/refman/py_python_api_overview.html#sec:Python Gurobi-Python].

{{File

module load gurobi

# Create environment file in current directory setting the number of threads:

echo "Threads ${SLURM_CPUS_ON_NODE:-1}" > gurobi.env

gurobi.sh  ${GUROBI_HOME}/examples/python/facility.py

}}

Gurobi brings it's own version of Python but that one does not contain any 3rd-party Python packages except Gurobi.  In order to use Gurobi together with popular Python  

packages like NumPy, Matplotlib, Pandas and others, we need to create a [[Python#Creating_and_using_a_virtual_environment|virtual Python environment]] in which we can install both <code>gurobipy</code> and e.g. <code>pandas</code>.

Before we start, we need to decide which combination of versions for Gurobi and Python to use.

<translate>

We see that <code>gurobi/8.1.1</code> brings it's own installation of <code>python2.7/</code> and Python packages for Python 2.7, 3.5, 3.6 and 3.7 (<code>pythonX.Y_utf32/</code>),

while <code>gurobi/9.0.1</code> by default uses <code>python3.7/</code> and brings Python packages for Python 2.7, 3.5, 3.6, 3.7 and 3.8 (<code>pythonX.Y_utf32/</code>).

In this example we want to create a Python environment based on <code>python/3.7</code> in which we want to use <code>gurobi/9.0.1</code> and install the Pandas package.

These steps need to be done only once per system.  

The first step is to load the modules, [[Python#Creating_and_using_a_virtual_environment|create the virtual environment]] and activate it.

{{Commands|prompt=[name@server ~] $

| module load gurobi/9.0.1 python/3.7

}}

Now that the environment has been activated we can install the Python packages we want to use, in this case <code>pandas</code>.

{{Commands|prompt=(env_gurobi) [name@server ~] $

| pip install --no-index  pandas

}}

The third step is to install gurobipy into the environment:

{{Commands|prompt=(env_gurobi) [name@server ~] $

| cd $EBROOTGUROBI

}}

Python scripts can now import both Pandas and Gurobi:

  import numpy as np

  import gurobipy as gurobi

  # [...]

Once created we can activate Gurobi and the environment with:

  source ~/env_gurobi/bin/activate

  python  my_gurobi_script.py

Note that we now use <code>python</code> instead of <code>gurobi.sh</code>!

And this is an example job script that we can use:

<translate>

Please see [https://support.gurobi.com/hc/en-us/articles/360013195592-How-do-I-cite-Gurobi-software-for-an-academic-publication- How do I cite Gurobi software for an academic publication?]

</translate>