solvers.py 文件源码

def actualSolve(self, lp):
        """Solve a well formulated lp problem"""
        if not self.executable(self.path):
            raise 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 = 1)
        try: os.remove(tmpSol)
        except: pass
        cmd = self.path
        cmd += ' ' + ' '.join(['%s=%s' % (key, value)
                    for key, value in self.options])
        cmd += ' ResultFile=%s' % tmpSol
        if lp.isMIP():
            if not self.mip:
                warnings.warn('GUROBI_CMD does not allow a problem to be relaxed')
        cmd += ' %s' % tmpLp
        if self.msg:
            pipe = None
        else:
            pipe = open(os.devnull, 'w')

        return_code = subprocess.call(cmd.split(), stdout = pipe, stderr = pipe)

        if return_code != 0:
            raise PulpSolverError("PuLP: Error while trying to execute "+self.path)
        if not self.keepFiles:
            try: os.remove(tmpLp)
            except: pass
        if not os.path.exists(tmpSol):
            warnings.warn('GUROBI_CMD does provide good solution status of non optimal solutions')
            status = LpStatusNotSolved
        else:
            status, values, reducedCosts, shadowPrices, slacks = self.readsol(tmpSol)
        if not self.keepFiles:
            try: os.remove(tmpSol)
            except: pass
            try: os.remove("gurobi.log")
            except: pass
        if status != LpStatusInfeasible:
            lp.assignVarsVals(values)
            lp.assignVarsDj(reducedCosts)
            lp.assignConsPi(shadowPrices)
            lp.assignConsSlack(slacks)
        lp.status = status
        return status