def readsol(self, filename):
"""Read a SCIP solution file"""
with open(filename) as f:
m = re.match(r"^solution status: (.*)", f.readline().strip())
if not m:
raise pulp.PulpSolverError("Unknown status returned by SCIP")
statusString = m.group(1)
scipStatus = {
"unknown": pulp.LpStatusNotSolved,
"user interrupt": pulp.LpStatusNotSolved,
"node limit reached": pulp.LpStatusNotSolved,
"total node limit reached": pulp.LpStatusNotSolved,
"stall node limit reached": pulp.LpStatusNotSolved,
"time limit reached": pulp.LpStatusOptimal,
"memory limit reached": pulp.LpStatusNotSolved,
"gap limit reached": pulp.LpStatusOptimal,
"solution limit reached": pulp.LpStatusNotSolved,
"solution improvement limit reached": pulp.LpStatusNotSolved,
"optimal solution found": pulp.LpStatusOptimal,
"infeasible": pulp.LpStatusInfeasible,
"unbounded": pulp.LpStatusUnbounded,
"infeasible or unbounded": pulp.LpStatusNotSolved,
}
if statusString not in scipStatus:
raise pulp.PulpSolverError("Unknown status returned by SCIP")
status = scipStatus[statusString]
f.readline() # objective value:
values = {}
for line in f:
name, val, _ = line.split()
values[name] = float(val)
return status, values
def actualSolve(self, lp):
"""Solve a well formulated lp problem"""
if not self.executable(self.path):
raise pulp.PulpSolverError("PuLP: cannot execute " + self.path)
if not self.keepFiles:
pid = os.getpid()
tmpLp = os.path.join(self.tmpDir, "%d-pulp.lp" % pid)
tmpSol = os.path.join(self.tmpDir, "%d-pulp.sol" % pid)
else:
tmpLp = lp.name + "-pulp.lp"
tmpSol = lp.name + "-pulp.sol"
lp.writeLP(tmpLp, writeSOS=0)
#proc = ["scip", "-c", "read \"%s\"" % tmpLp, "-c", "set limits time 180", "-c", "optimize", "-c", "write solution \"%s\"" % tmpSol, "-c", "quit"]
proc = ["scip", "-c", "read \"%s\"" % tmpLp]
if self.time_limit is not None:
proc += ["-c", "set limits time %f" % self.time_limit]
if self.ratio_gap is not None:
proc += ["-c", "set limits gap %f" % self.ratio_gap]
proc += [
"-c", "optimize", "-c",
"write solution \"%s\"" % tmpSol, "-c", "quit"
]
proc.extend(self.options)
self.solution_time = clock()
if not self.msg:
proc[0] = self.path
pipe = open(os.devnull, 'w')
rc = subprocess.call(proc, stdout=pipe, stderr=pipe)
if rc:
raise pulp.PulpSolverError(
"PuLP: Error while trying to execute " + self.path)
else:
if os.name != 'nt':
rc = os.spawnvp(os.P_WAIT, self.path, proc)
else:
rc = os.spawnv(os.P_WAIT, self.executable(self.path), proc)
if rc == 127:
raise pulp.PulpSolverError(
"PuLP: Error while trying to execute " + self.path)
self.solution_time += clock()
if not os.path.exists(tmpSol):
raise pulp.PulpSolverError("PuLP: Error while executing " +
self.path)
lp.status, values = self.readsol(tmpSol)
lp.assignVarsVals(values)
if not self.keepFiles:
try:
os.remove(tmpLp)
except:
pass
try:
os.remove(tmpSol)
except:
pass
return lp.status
