4

I'm running PuLP on OS X via a iPython notebook and Python 2.7. glpk is installed using brew install homebrew/science/glpk and PuLP is installed via pip install pulp.

However I'm getting the error in Python: 

---------------------------------------------------------------------------
PulpSolverError                           Traceback (most recent call last)
<ipython-input-15-689fef0dd94f> in <module>()
      1 # Solve the problem
----> 2 status = prob.solve(GLPK(msg=0))
      3 

/Users/x/anaconda/envs/data/lib/python2.7/site-packages/pulp/pulp.pyc in solve(self, solver, **kwargs)
   1641         #time it
   1642         self.solutionTime = -clock()
-> 1643         status = solver.actualSolve(self, **kwargs)
   1644         self.solutionTime += clock()
   1645         self.restoreObjective(wasNone, dummyVar)

/Users/x/anaconda/envs/data/lib/python2.7/site-packages/pulp/solvers.pyc in actualSolve(self, lp)
    364                              stderr = pipe)
    365             if rc:
--> 366                 raise PulpSolverError("PuLP: Error while trying to execute "+self.path)
    367         else:
    368             if os.name != 'nt':

PulpSolverError: PuLP: Error while trying to execute glpsol

Here's the code that triggers this error:

from pulp import *

#Variables
x = LpVariable('x')
y = LpVariable('y')

# Problem
prob = LpProblem('problem', LpMinimize)

# Constraints
prob += x + y <= 1
prob += x <= 1
prob += -2 + y <= 4

# Objective function to minimize
prob += 

# Solve the problem
status = prob.solve(GLPK(msg=0))

What's causing the error, and how can it be fixed?

Nyxynyx
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2 Answers2

2

If you run 

pulp.pulpTestAll()

you probably will see a line like this:

Solver pulp.solvers.GLPK_CMD unavailable

If so, all you have to do is to install glpk-utils package on your linux. If you succeeded with it, you should be able to call

glpsol

from command line, too.

TorokLev
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1

I had the same error in Ubuntu and this solved it.

It is necessary to issue the following command after make install:

sudo ldconfig

Ldconfig creates the necessary links and cache to the most recent shared libraries.

https://lists.gnu.org/archive/html/help-glpk/2013-09/msg00018.html

arimbr
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