pulp.apis.core.PulpSolverError: Pulp: cannot execute cbc.exe

[p91g]

Hello,

I am trying to execute the following:

solver = pulp.COIN_CMD(msg=True, warmStart=True)

pcenter_from_cm = PCenter.from_cost_matrix(
    distances, p_facilities=facilities, name="p-center-network-distance"
)

pcenter_from_cm = pcenter_from_cm.solve(solver)

But get the following error:

pcenter_from_cm = pcenter_from_cm.solve(solver)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\x\Documents\spopt_venv\lib\site-packages\spopt\locate\p_center.py", line 409, in solve
    self.problem.solve(solver)
  File "C:\Users\x\Documents\spopt_venv\lib\site-packages\pulp\pulp.py", line 1913, in solve
    status = solver.actualSolve(self, **kwargs)
  File "C:\Users\x\Documents\spopt_venv\lib\site-packages\pulp\apis\coin_api.py", line 137, in actualSolve
    return self.solve_CBC(lp, **kwargs)
  File "C:\Users\x\Documents\spopt_venv\lib\site-packages\pulp\apis\coin_api.py", line 146, in solve_CBC
    raise PulpSolverError(
pulp.apis.core.PulpSolverError: Pulp: cannot execute cbc.exe cwd: C:\Users\x\Documents\

Does anybody have any suggestions?

I have tried passing the msg=1 argument to the solver, to get more information.

I have checked the precision of the numbers, rounding them.

The cost distance matrix is is a pairwise distance matrix of one df of points - i.e. with itself. Could it be that it is due to duplicated variables / constraints?

[jGaboardi]

As per the error message, the problem appears to be with your pulp installation. How did you install pulp?

Also, please provide:

• the version of spopt and pulp you are using
• a Minimal Working Example. The code chunk you provided seems to be from one of the notebooks in the repo.

[p91g]

Thank you for the quick response!

I used pip install for pulp - version 2.7.0

Spopt - version 0.5.0

Example code

import spopt
from spopt.locate import PCenter
import geopandas as gpd
import shapely 
from shapely import Point
import pandas as pd
import numpy as np
import pulp
import scipy

grid = pd.read_csv(r"C:\Users\x\Documents\city_spatial_analysis\station_allocation\grid_coords.csv")
grid = grid[['index', 'lon', 'lat']]

# number of candidate facilities in optimal solution 
facilities = 35

# set the solver
solver = pulp.COIN_CMD(msg=True, warmStart=True)

# calculate network distance cost matrix
distances = scipy.spatial.distance.squareform(scipy.spatial.distance.pdist(grid [["lon", "lat"]]))

# replacing zeros with 50,000
distances = np.where(distances== 0, 50000, distances)
distances = np.round(distances)

pcenter_from_cm = PCenter.from_cost_matrix(
    distances, p_facilities=facilities, name="p-center-network-distance"
)

pcenter_from_cm = pcenter_from_cm.solve(solver)

[jGaboardi]

For the code chunk above to run (be on the way to a MWE), you will need to provide grid_coords.csv. However, I would suggest you try both conda install pulp and pip install pulp, then try to run your code again.

[p91g]

My bad, here are some simulated points taken from the tutorial page for p-center. The same error occurs. I have tried uninstalling and pip installing pulp again, but the same error happens. I am not using coda. I will try using anaconda and a new env perhaps.

import spopt
#from spopt.locate import MCLP, simulated_geo_points 
from spopt.locate import PMedian
from spopt.locate import PCenter, simulated_geo_points
import geopandas as gpd
import shapely 
from shapely import Point
#import matplotlib.pyplot as plt
#from matplotlib.patches import Patch
import pandas as pd
import numpy as np
import pulp
import scipy

import warnings
with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    # ignore deprecation warning - GH pysal/spaghetti#649
    import spaghetti

# quantity demand points
CLIENT_COUNT = 176

# number of candidate facilities in optimal solution
P_FACILITIES = 35

# random seeds for reproducibility
CLIENT_SEED = 5
FACILITY_SEED = 6

# set the solver
solver = pulp.COIN_CMD(msg=False, warmStart=True)

with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    # ignore deprecation warning - GH pysal/libpysal#468
    lattice = spaghetti.regular_lattice((0, 0, 10, 10), 9, exterior=True)
ntw = spaghetti.Network(in_data=lattice)

streets = spaghetti.element_as_gdf(ntw, arcs=True)

streets_buffered = gpd.GeoDataFrame(
    gpd.GeoSeries(streets["geometry"].buffer(0.5).unary_union),
    crs=streets.crs,
    columns=["geometry"],
)

client_points = simulated_geo_points(
    streets_buffered, needed=CLIENT_COUNT, seed=CLIENT_SEED
)

with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    # ignore deprecation warning - GH pysal/libpysal#468
    ntw.snapobservations(client_points, "clients", attribute=True)

clients_snapped = spaghetti.element_as_gdf(ntw, pp_name="clients", snapped=True)
clients_snapped.drop(columns=["id", "comp_label"], inplace=True)


cost_matrix = ntw.allneighbordistances(
    sourcepattern=ntw.pointpatterns["clients"],
    destpattern=ntw.pointpatterns["clients"],
)

cost_matrix = np.where(cost_matrix== 0, 50000, cost_matrix)
cost_matrix = np.round(cost_matrix)

pcenter_from_cm = PCenter.from_cost_matrix(
    cost_matrix, p_facilities=P_FACILITIES, name="p-center-network-distance"
)

pcenter_from_cm = pcenter_from_cm.solve(solver)

[jGaboardi]

Did you install spopt via pip or conda/mamba?

We need to update the docs here to say "highly recommend conda/etc. over pip" like we do across other PySAL packages, e.g. in spaghetti.

[p91g]

I installed with pip. I have now tried installing via conda and installing using conda install, but get the same error unfortunately.

[jGaboardi]

Try :

1. pip install pulp
2. then run pulptest (see here)
3. then (without removing pulp) conda install pulp.
4. then try running the code again

[p91g]

Thank you. Unfortunately that didn't work. The same error is there. I got the following for the pulp test. Nothing showing as unavailable but it does look different to the code the pulp page suggests i should see.

pulp.pulpTestAll()
sssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss
Test that logic put in place for deprecation handling of indexs works
Testing 'indexs' param continues to work for LpVariable.dicts
Testing 'indexs' param continues to work for LpVariable.matrix
Testing 'indices' argument works in LpVariable.dicts
Testing 'indices' param continues to work for LpVariable.matrix
Testing invalid status
Testing continuous LP solution - export dict
Testing export dict for LP
Testing export dict MIP
Testing maximize continuous LP solution
Testing continuous LP solution - export JSON
Testing continuous LP solution - export solver dict
Testing continuous LP solution - export solver JSON
Testing reading MPS files - binary variable, no constraint names
Testing reading MPS files - integer variable
Testing reading MPS files - maximize
...................
Testing reading MPS files - noname
Testing invalid var names
Testing makeDict general behavior
Testing makeDict default value behavior
Testing measuring optimization time
Testing that readsol can parse CPLEX mipopt solution
Testing the availability of the function pulpTestAll
Testing zero subtraction
Testing inconsistent lp solution
Testing continuous LP solution
Testing maximize continuous LP solution
Testing unbounded continuous LP solution
Testing Long Names
Testing repeated Names
Testing zero constraint
Testing zero objective
Testing LpVariable (not LpAffineExpression) objective
............
Testing LpAffineExpression divide
Testing MIP solution
Testing MIP solution with floats in objective
Testing Initial value in MIP solution
Testing fixing value in MIP solution
Testing MIP relaxation
Testing feasibility problem (no objective)
Testing an infeasible problem
Testing an integer infeasible problem
Testing another integer infeasible problem
Testing column based modelling
sssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss
Testing fractional constraints
Testing elastic constraints (no change)
Testing elastic constraints (freebound)
Testing elastic constraints (penalty unchanged)
Testing elastic constraints (penalty unbounded)
Testing timeLimit argument
ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss

Ran 1003 tests in 2.016s

OK (skipped=944)

[jGaboardi]

Can you post your full environment file (see here)?

[p91g]

Thank you so much for your help on this. Attached is the environment file.

spopt_env_copy.zip

[Anran0716]

I encountered the similar issue about this too when running the code mclp.ipynb:
Pulp: cannot execute cbc.exe cwd: C:\Users\zheng\Dropbox (UFL)\Gap analysis\code\spopt-main\spopt-main\notebooks
Looking forward to the reply! Thank you so much!

[gegen07]

Hey there! Installing pulp via pip/conda does not install COIN_CMD. To use this solver, you should have CBC installed in your environment. See the instruction here.

If this error persists, please let us know.

By the way, the pip install pulp installs automatically PULP_CBC_CMD so you can use that instead COIN_CMD.

[Anran0716]

I encountered the similar issue about this too when running the code mclp.ipynb: Pulp: cannot execute cbc.exe cwd: C:\Users\zheng\Dropbox (UFL)\Gap analysis\code\spopt-main\spopt-main\notebooks Looking forward to the reply! Thank you so much!

I have solved my problem with this code:
'solver = pl.PULP_CBC_CMD(keepFiles=True)

[p91g]

Nice one, thank you! 'solver = pl.PULP_CBC_CMD(keepFiles=True)' also worked for me it seems. Appreciate the help.

[jGaboardi]

Thanks for troubleshooting @gegen07 .