| |||||||||||||
| |||||||||||||
Loading a problem Description Shows how to directly load a problem and solve it in Python Further explanation of this example: 'Xpress Python Reference Manual'
Source Files By clicking on a file name, a preview is opened at the bottom of this page.
loadproblem.py
# Example of using the load*() functions for several problem types.
#
# Usage: define PROBTYPE parameter.
#
# (C) 1983-2025 Fair Isaac Corporation
import xpress as xp
PROBTYPE = 'LP'
'''Select problem type:
'LP': LP problem with three variables and four constraints
'QP': LP with a quadratic objective
'QCQP': quadratically constrained quadratic problem
'MIQCQP': QCQP where variables are integer or binary
'MIQCQPSOS': MIQCQP with Special Ordered Sets (SOSs)
'''
def loadlp():
'''LP problem with three variables and four constraints.'''
p = xp.problem()
# Fill in an LP problem with three variables and four constraints.
p.loadLP("", # probname
['G', 'G', 'E', 'L'], # rowtype
[-2.4, -3, 4, 5], # rhs
None, # rng
[3, 4, 5], # objcoef
[0, 2, 4, 8], # start
None, # collen
[0, 1, 2, 3, 0, 1, 2, 3], # rowind
[1, 1, 1, 1, 1, 1, 1, 1], # rowcoef
[-1, -1, -1], # lb
[3, 5, 8]) # ub
p.writeProb("loadedlp", "lp")
p.optimize()
# Get a variable and modify the objective
# function. Note that the objective function is replaced by, not
# amended with, the new objective.
x1 = p.getVariable(0)
p.setObjective(x1 ** 2 + 2 * x1 + 444)
p.optimize()
p.writeProb("updatedlp", "lp")
def loadqp():
'''LP problem with a quadratic objective.'''
p = xp.problem()
# Fill in a QP problem with three variables and four constraints.
p.loadQP("", # probname
['G', 'G', 'E', 'L'], # rowtype
[-2.4, -3, 4, 5], # rhs
None, # rng
[3, 4, 5], # objcoef
[0, 2, 4, 8], # start
None, # collen
[0, 1, 2, 3, 0, 1, 2, 3], # rowind
[1, 1, 1, 1, 1, 1, 1, 1], # rowcoef
[-1, -1, -1], # lb
[3, 5, 8], # ub
[0, 0, 0, 1, 1, 2], # objqcol1
[0, 1, 2, 1, 2, 2], # objqcol2
[2, 1, 1, 2, 1, 2]) # objqcoef
p.writeProb("loadedqp", "lp")
p.optimize()
def loadqcqp():
'''Quadratically constrained quadratic problem.'''
p = xp.problem()
# Fill in a QCQP problem with three variables and four constraints.
p.loadQCQP("", # probname
['G', 'G', 'L', 'L'], # rowtype
[-2.4, -3, 4, 5], # rhs
None, # rng
[3, 4, 5], # objcoef
[0, 2, 4, 8], # start
None, # collen
[0, 1, 2, 3, 0, 1, 2, 3], # rowind
[1, 1, 1, 1, 1, 1, 1, 1], # rowcoef
[-1, -1, -1], # lb
[3, 5, 8], # ub
[0, 0, 0, 1, 1, 2], # objqcol1
[0, 1, 2, 1, 2, 2], # objqcol2
[2, 1, 1, 2, 1, 2], # objqcoef
[2, 3], # qrowind
[2, 3], # nrowqcoef
[1, 2, 0, 0, 2], # rowqcol1
[1, 2, 0, 2, 2], # rowqcol2
[3, 4, 1, 1, 1]) # rowqcoef
p.writeProb("loadedqcqp", "lp")
p.optimize()
def loadmiqcqp():
'''QCQP where variables are integer or binary.'''
p = xp.problem()
# Fill in an MIQCQP problem with three variables and four constraints.
p.loadMIQCQP("", # probname
['G', 'G', 'L', 'L'], # rowtype
[-2.4, -3, 4, 5], # rhs
None, # rng
[3, 4, 5], # objcoef
[0, 2, 4, 8], # start
None, # collen
[0, 1, 2, 3, 0, 1, 2, 3], # rowind
[1, 1, 1, 1, 1, 1, 1, 1], # rowcoef
[-1, -1, -1], # lb
[3, 5, 8], # ub
[0, 0, 0, 1, 1, 2], # objqcol1
[0, 1, 2, 1, 2, 2], # objqcol2
[2, 1, 1, 2, 1, 2], # objqcoef
[2, 3], # qrowind
[2, 3], # nrowqcoefs
[1, 2, 0, 0, 2], # rowqcol1
[1, 2, 0, 2, 2], # rowqcol2
[3, 4, 1, 1, 1], # rowqcoef
['I', 'S'], # coltype
[0, 1], # entind
[0, 2]) # limit
p.writeProb("loadedmiqcqp", "lp")
p.optimize()
print(p.getSolution())
def loadmiqcqp_sos():
'''MIQCQP with Special Ordered Sets (SOSs).'''
p = xp.problem()
# Fill in an MIQCQP problem with two Special Ordered Sets (SOSs).
p.loadMIQCQP("", # probname
['G', 'G', 'L', 'L'], # rowtype
[-2.4, -3, 4, 5], # rhs
None, # rng
[3, 4, 5], # objcoef
[0, 2, 4, 8], # start
None, # collen
[0, 1, 2, 3, 0, 1, 2, 3], # rowind
[1, 1, 1, 1, 1, 1, 1, 1], # rowcoef
[-1, -1, -1], # lb
[3, 5, 8], # ub
[0, 0, 0, 1, 1, 2], # objqcol1
[0, 1, 2, 1, 2, 2], # objqcol2
[2, 1, 1, 2, 1, 2], # objqcoef
[2, 3], # qrowind
[2, 3], # nrowqcoefs
[1, 2, 0, 0, 2], # rowqcol1
[1, 2, 0, 2, 2], # rowqcol2
[3, 4, 1, 1, 1], # rowqcoef
['I', 'S'], # coltype
[0, 1], # entind
[0, 2], # limit
['1', '1'], # settype
[0, 2, 4], # setstart
[0, 1, 0, 2], # setind
[1.1, 1.2, 1.3, 1.4]) # refval
p.writeProb("loadedmiqcqp_sos", "lp")
p.optimize()
print(p.getSolution())
if PROBTYPE == 'LP':
loadlp()
elif PROBTYPE == 'QP':
loadqp()
elif PROBTYPE == 'QCQP':
loadqcqp()
elif PROBTYPE == 'MIQCQP':
loadmiqcqp()
elif PROBTYPE == 'MIQCQPSOS':
loadmiqcqp_sos()
else:
print("Invalid choice of PROBTYPE parameter. Please try again.")
| |||||||||||||
| © Copyright 2025 Fair Isaac Corporation. |
