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

In order to install it I did as follows: enter image description here

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

enter image description here

How can I resolve it ?

Optimization team
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3 Answers3

6

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))
Stefano Gualandi
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Optimization team
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  • thanks is it possible to show how to use the same approach for MINLP ? how can I give the address of solver ? for example, instaed of using your ipopt address which one of these can be used ? https://www.coin-or.org/download/binary/Ipopt/ – Optimization team Feb 25 '23 at 01:12
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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).

Stefano Gualandi
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    Hi Stefano, https://ampl.com/dl/open/ipopt/ipopt-linux64.zip no longer exists – Optimization team Feb 21 '23 at 22:21
  • This is a pity. We should look for an alternative website with that code. Thanks for letting us know about it. – Stefano Gualandi Feb 22 '23 at 07:59
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    @Optimizationteam I stored the ipopt file somewhere else (and I hope nobody complaints about it). – Stefano Gualandi Feb 22 '23 at 12:36
  • I understand, my question is when I give the address of ipopt or other coin-or solvers it does not work

    how can I use your approach for otehr solvers ? https://www.coin-or.org/download/source/

     – Optimization team Feb 26 '23 at 11:59
  • I tried all the methods in this answer, but mostly I'm getting the error : [ipopt-linux64.zip] End-of-central-directory signature not found. Either this file is not a zipfile, or it constitutes one disk of a multi-part archive. In the latter case the central directory and zipfile comment will be found on the last disk(s) of this archive. unzip: cannot find zipfile directory in one of ipopt-linux64 or ipopt-linux64.zip, and cannot find ipopt-linux64.ZIP, period. – Another Random Guy Jun 21 '23 at 05:27
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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

Meriem
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