Scippy

SCIP

Solving Constraint Integer Programs

Detailed Description

LNS heuristic that tries to randomly mutate the incumbent solution.

Author
Timo Berthold

Definition in file heur_mutation.c.

#include "blockmemshell/memory.h"
#include "scip/heuristics.h"
#include "scip/heur_mutation.h"
#include "scip/pub_heur.h"
#include "scip/pub_message.h"
#include "scip/pub_misc.h"
#include "scip/pub_sol.h"
#include "scip/pub_var.h"
#include "scip/scip_branch.h"
#include "scip/scip_cons.h"
#include "scip/scip_copy.h"
#include "scip/scip_general.h"
#include "scip/scip_heur.h"
#include "scip/scip_mem.h"
#include "scip/scip_message.h"
#include "scip/scip_nodesel.h"
#include "scip/scip_numerics.h"
#include "scip/scip_param.h"
#include "scip/scip_prob.h"
#include "scip/scip_randnumgen.h"
#include "scip/scip_sol.h"
#include "scip/scip_solve.h"
#include "scip/scip_solvingstats.h"
#include <string.h>

Go to the source code of this file.

Macros

#define HEUR_NAME   "mutation"
 
#define HEUR_DESC   "mutation heuristic randomly fixing variables"
 
#define HEUR_DISPCHAR   SCIP_HEURDISPCHAR_LNS
 
#define HEUR_PRIORITY   -1103010
 
#define HEUR_FREQ   -1
 
#define HEUR_FREQOFS   8
 
#define HEUR_MAXDEPTH   -1
 
#define HEUR_TIMING   SCIP_HEURTIMING_AFTERNODE
 
#define HEUR_USESSUBSCIP   TRUE
 
#define DEFAULT_NODESOFS   500
 
#define DEFAULT_MAXNODES   5000
 
#define DEFAULT_MINIMPROVE   0.01
 
#define DEFAULT_MINNODES   500
 
#define DEFAULT_MINFIXINGRATE   0.8
 
#define DEFAULT_NODESQUOT   0.1
 
#define DEFAULT_NWAITINGNODES   200
 
#define DEFAULT_USELPROWS   FALSE
 
#define DEFAULT_COPYCUTS   TRUE
 
#define DEFAULT_BESTSOLLIMIT   -1
 
#define DEFAULT_USEUCT   FALSE
 
#define DEFAULT_RANDSEED   19
 

Functions

static SCIP_RETCODE determineVariableFixings (SCIP *scip, SCIP_VAR **fixedvars, SCIP_Real *fixedvals, int *nfixedvars, SCIP_Real minfixingrate, SCIP_RANDNUMGEN *randnumgen, SCIP_Bool *success)
 
static SCIP_RETCODE setupAndSolveSubscipMutation (SCIP *scip, SCIP *subscip, SCIP_HEUR *heur, SCIP_VAR **fixedvars, SCIP_Real *fixedvals, int nfixedvars, SCIP_Longint nsubnodes, SCIP_RESULT *result)
 
static SCIP_DECL_HEURCOPY (heurCopyMutation)
 
static SCIP_DECL_HEURFREE (heurFreeMutation)
 
static SCIP_DECL_HEURINIT (heurInitMutation)
 
static SCIP_DECL_HEUREXIT (heurExitMutation)
 
static SCIP_DECL_HEUREXEC (heurExecMutation)
 
SCIP_RETCODE SCIPincludeHeurMutation (SCIP *scip)
 

Macro Definition Documentation

◆ HEUR_NAME

#define HEUR_NAME   "mutation"

Definition at line 58 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_DESC

#define HEUR_DESC   "mutation heuristic randomly fixing variables"

Definition at line 59 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_DISPCHAR

#define HEUR_DISPCHAR   SCIP_HEURDISPCHAR_LNS

Definition at line 60 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_PRIORITY

#define HEUR_PRIORITY   -1103010

Definition at line 61 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_FREQ

#define HEUR_FREQ   -1

Definition at line 62 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_FREQOFS

#define HEUR_FREQOFS   8

Definition at line 63 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_MAXDEPTH

#define HEUR_MAXDEPTH   -1

Definition at line 64 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_TIMING

#define HEUR_TIMING   SCIP_HEURTIMING_AFTERNODE

Definition at line 65 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP   TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 66 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_NODESOFS

#define DEFAULT_NODESOFS   500

number of nodes added to the contingent of the total nodes

Definition at line 68 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_MAXNODES

#define DEFAULT_MAXNODES   5000

maximum number of nodes to regard in the subproblem

Definition at line 69 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_MINIMPROVE

#define DEFAULT_MINIMPROVE   0.01

factor by which Mutation should at least improve the incumbent

Definition at line 70 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_MINNODES

#define DEFAULT_MINNODES   500

minimum number of nodes to regard in the subproblem

Definition at line 71 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_MINFIXINGRATE

#define DEFAULT_MINFIXINGRATE   0.8

minimum percentage of integer variables that have to be fixed

Definition at line 72 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_NODESQUOT

#define DEFAULT_NODESQUOT   0.1

subproblem nodes in relation to nodes of the original problem

Definition at line 73 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_NWAITINGNODES

#define DEFAULT_NWAITINGNODES   200

number of nodes without incumbent change that heuristic should wait

Definition at line 74 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_USELPROWS

#define DEFAULT_USELPROWS   FALSE

should subproblem be created out of the rows in the LP rows, otherwise, the copy constructors of the constraints handlers are used

Definition at line 75 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_COPYCUTS

#define DEFAULT_COPYCUTS   TRUE

if DEFAULT_USELPROWS is FALSE, then should all active cuts from the cutpool of the original scip be copied to constraints of the subscip

Definition at line 78 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_BESTSOLLIMIT

#define DEFAULT_BESTSOLLIMIT   -1

limit on number of improving incumbent solutions in sub-CIP

Definition at line 81 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_USEUCT

#define DEFAULT_USEUCT   FALSE

should uct node selection be used at the beginning of the search?

Definition at line 82 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_RANDSEED

#define DEFAULT_RANDSEED   19

initial random seed

Definition at line 83 of file heur_mutation.c.

Function Documentation

◆ determineVariableFixings()

static SCIP_RETCODE determineVariableFixings ( SCIP scip,
SCIP_VAR **  fixedvars,
SCIP_Real fixedvals,
int *  nfixedvars,
SCIP_Real  minfixingrate,
SCIP_RANDNUMGEN randnumgen,
SCIP_Bool success 
)
static

determine variables and values which should be fixed in the mutation subproblem

Parameters
sciporiginal SCIP data structure
fixedvarsarray to store the variables that should be fixed in the subproblem
fixedvalsarray to store the fixing values to fix variables in the subproblem
nfixedvarspointer to store the number of variables that should be fixed
minfixingratepercentage of integer variables that have to be fixed
randnumgenrandom number generator
successused to store whether the creation of the subproblem worked

Definition at line 115 of file heur_mutation.c.

References BMScopyMemoryArray, FALSE, NULL, REALABS, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPgetBestSol(), SCIPgetSolVal(), SCIPgetVarsData(), SCIPisGT(), SCIPisInfinity(), SCIPisLE(), SCIPisLT(), SCIPrandomPermuteArray(), SCIPvarGetLbGlobal(), SCIPvarGetUbGlobal(), setupAndSolveSubscipMutation(), and TRUE.

◆ setupAndSolveSubscipMutation()

static SCIP_RETCODE setupAndSolveSubscipMutation ( SCIP scip,
SCIP subscip,
SCIP_HEUR heur,
SCIP_VAR **  fixedvars,
SCIP_Real fixedvals,
int  nfixedvars,
SCIP_Longint  nsubnodes,
SCIP_RESULT result 
)
static

setup and solve mutation sub-SCIP

Parameters
scipSCIP data structure
subscipsub-SCIP data structure
heurmutation heuristic
fixedvarsarray to store the variables that should be fixed in the subproblem
fixedvalsarray to store the fixing values to fix variables in the subproblem
nfixedvarsthe number of variables that should be fixed
nsubnodesnode limit for the subproblem
resultpointer to store the result

Definition at line 197 of file heur_mutation.c.

References FALSE, NULL, SCIP_Bool, SCIP_CALL, SCIP_CALL_ABORT, SCIP_DECL_HEURCOPY(), SCIP_FOUNDSOL, SCIP_OKAY, SCIP_PARAMSETTING_FAST, SCIP_PARAMSETTING_OFF, SCIP_Real, SCIPallocBufferArray, SCIPblkmem(), SCIPcopyLargeNeighborhoodSearch(), SCIPcopyLimits(), SCIPdebug, SCIPdebugMsg, SCIPfindBranchrule(), SCIPfindNodesel(), SCIPfreeBufferArray, SCIPgetLowerbound(), SCIPgetNNodes(), SCIPgetNVars(), SCIPgetUpperbound(), SCIPgetVars(), SCIPhashmapCreate(), SCIPhashmapFree(), SCIPhashmapGetImage(), SCIPheurGetData(), SCIPisInfinity(), SCIPisParamFixed(), SCIPmergeVariableStatistics(), SCIPprintStatistics(), SCIPsetBoolParam(), SCIPsetCharParam(), SCIPsetIntParam(), SCIPsetLongintParam(), SCIPsetObjlimit(), SCIPsetPresolving(), SCIPsetSeparating(), SCIPsetSubscipsOff(), SCIPsolve(), SCIPsumepsilon(), SCIPtranslateSubSols(), and TRUE.

Referenced by determineVariableFixings().

◆ SCIP_DECL_HEURCOPY()

static SCIP_DECL_HEURCOPY ( heurCopyMutation  )
static

copy method for primal heuristic plugins (called when SCIP copies plugins)

Definition at line 362 of file heur_mutation.c.

Referenced by setupAndSolveSubscipMutation().

◆ SCIP_DECL_HEURFREE()

static SCIP_DECL_HEURFREE ( heurFreeMutation  )
static

destructor of primal heuristic to free user data (called when SCIP is exiting)

Definition at line 376 of file heur_mutation.c.

◆ SCIP_DECL_HEURINIT()

static SCIP_DECL_HEURINIT ( heurInitMutation  )
static

initialization method of primal heuristic (called after problem was transformed)

Definition at line 396 of file heur_mutation.c.

◆ SCIP_DECL_HEUREXIT()

static SCIP_DECL_HEUREXIT ( heurExitMutation  )
static

deinitialization method of primal heuristic

Definition at line 419 of file heur_mutation.c.

◆ SCIP_DECL_HEUREXEC()

static SCIP_DECL_HEUREXEC ( heurExecMutation  )
static

execution method of primal heuristic

Definition at line 438 of file heur_mutation.c.