How to install Ipopt on Google Colab for Pyomo?

Question

I need to use Pyomo with Ipopt solver on Google-Colab.

In order to install it I did as follows:

Now I need to use it , I get the following error ? ApplicationError: No executable found for solver 'ipopt'

How can I resolve it ?

Answer 1

The following package installation should be done before staring the Pyomo model

!pip install pyomo 
from pyomo.environ import *
import matplotlib.pyplot as plt
!wget -N -q "https://matematica.unipv.it/gualandi/solvers/ipopt-linux64.zip"
!unzip -o -q ipopt-linux64

Then you can run your NLP model

model = AbstractModel()
model.x = Var(bounds=(0,1.2), within=Reals)
model.obj1 = Objective(expr=model.x**2, sense=maximize)
#opt = SolverFactory('ipopt')
opt=SolverFactory('ipopt', executable='/content/ipopt')
instance = model.create_instance()
results = opt.solve(instance) # solves and updates instance
print('OF= ',value(instance.obj1))

Answer 2

If your notebook could be executed both on Colab or on a different environment (such as a local Jupyter notebook), you could add a couple of checks, before downloading and reinstalling pyomo and ipopt every time, as follows:

import shutil
import sys
import os.path

if not shutil.which("pyomo"):
    !pip install -q pyomo
    assert(shutil.which("pyomo"))

if not (shutil.which("ipopt") or os.path.isfile("ipopt")):
    if "google.colab" in sys.modules:
        !wget -N -q "https://matematica.unipv.it/gualandi/solvers/ipopt-linux64.zip"
        !unzip -o -q ipopt-linux64
    else:
        try:
            !conda install -c conda-forge ipopt 
        except:
            pass

NOTE: I have modified the link to ipopt-linux64.zip on Feb. 22nd, 2023. Older binaries of IpOpt are available at COIN-OR

Thanks to Stefano Coniglio and Pietro Belotti for the support on this.

NOTE 2: Since it was asked in a comment, you can install GLPK as follows:

if not (shutil.which("glpk") or os.path.isfile("glpk")):
    if "google.colab" in sys.modules:
        !apt-get install -y -qq glpk-utils
    else:
        try:
            !conda install -c conda-forge glpk 
        except:
            pass

For other solvers, the process is quite similar (e.g., for CBC).

Answer 3

I found a link that works for installing the solver on windows, i dont know if that will help, but here it is :

https://www.youtube.com/watch?v=EB_qVoM74Fg