Change Solver in API/AMPL/R Interface

[Edwin Okoronkwo]

Hello,

I am new to using the API/AMPL interface with any of the programming languages and I am trying to go through an example using R. Below is the link:

https://ampl.com/api/nightly/R/quick-start.html

However, when I try to solve the example problem the system is unable to invoke the MINOS solver, see below. The AMPL program that I have access to has CPLEX solver and not MINOS.

So the question is: Is it possible to change the solver from MINOS to CPLEX in R Studio?

Can you advise on another method to setup CPLEX as the default solver?

library(rAMPL)
ampl <- new(AMPL)

# Interpret the two files
ampl$read("models/diet/diet.mod")
ampl$readData("models/diet/diet.dat")

# Solve
ampl$solve()

Cannot invoke minos: no such program.

Objective is: 0

Increased costs of beef and ham.

Cannot invoke minos: no such program.

New objective value: 0

Updated all costs.

Cannot invoke minos: no such program.

New objective value: 0

  index0 Buy.val

1   BEEF       0

2    CHK       0

3   FISH       0

4    HAM       0

5    MCH       0

6    MTL       0

7    SPG       0

8    TUR       0

  index0 X100.Buy.j...Buy.j..ub.

1   BEEF                       0

2    CHK                       0

3   FISH                       0

4    HAM                       0

5    MCH                       0

6    MTL                       0

7    SPG                       0

8    TUR                       0

[AMPL Google Group]

Dear Edwin,

You can change the solver to cplex with:

ampl$setOption("solver", "cplex")

or, alternatively:

ampl$setOption("solver", "/complete/path/to/cplex")

Best regards,
Filipe

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am...@googlegroups.com

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[Edwin Okoronkwo]

Dear Filipe,

Thanks. It's working now...simple answer to a big problem.

[agrecco]

Dear Edwin

Just for a help to solve this on Matlab
I got the same problem and I solved it writting the follow :
>>
firstExample cplex 'C:\Program Files
(x86)\amplide.mswin64\ampl.mswin64\models'

instead of: firstExample <solver> <modeldir>





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