Detailed Description

LNS heuristic that tries to randomly mutate the incumbent solution.

Author: Timo Berthold

#include <assert.h>
#include <string.h>
#include "scip/scip.h"
#include "scip/scipdefplugins.h"
#include "scip/cons_linear.h"
#include "scip/heur_mutation.h"
#include "scip/pub_misc.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 'M'

#define	HEUR_PRIORITY -1103000

#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 /* number of nodes added to the contingent of the total nodes */

#define	DEFAULT_MAXNODES 5000 /* maximum number of nodes to regard in the subproblem */

#define	DEFAULT_MINIMPROVE 0.01 /* factor by which Mutation should at least improve the incumbent */

#define	DEFAULT_MINNODES 500 /* minimum number of nodes to regard in the subproblem */

#define	DEFAULT_MINFIXINGRATE 0.8 /* minimum percentage of integer variables that have to be fixed */

#define	DEFAULT_NODESQUOT 0.1 /* subproblem nodes in relation to nodes of the original problem */

#define	DEFAULT_NWAITINGNODES 200 /* number of nodes without incumbent change that heuristic should wait */

#define	DEFAULT_USELPROWS

#define	DEFAULT_COPYCUTS

#define	DEFAULT_BESTSOLLIMIT -1 /* limit on number of improving incumbent solutions in sub-CIP */

#define	DEFAULT_USEUCT FALSE /* should uct node selection be used at the beginning of the search? */

#define	DEFAULT_RANDSEED 19 /* initial random seed */

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	createNewSol (SCIP scip, SCIP subscip, SCIP_VAR *subvars, SCIP_HEUR heur, SCIP_SOL subsol, 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 31 of file heur_mutation.c.

Referenced by SCIP_DECL_HEURCOPY(), and SCIPincludeHeurMutation().

◆ HEUR_DESC

#define HEUR_DESC "mutation heuristic randomly fixing variables"

Definition at line 32 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_DISPCHAR

#define HEUR_DISPCHAR 'M'

Definition at line 33 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_PRIORITY

#define HEUR_PRIORITY -1103000

Definition at line 34 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_FREQ

#define HEUR_FREQ -1

Definition at line 35 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_FREQOFS

#define HEUR_FREQOFS 8

Definition at line 36 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_MAXDEPTH

#define HEUR_MAXDEPTH -1

Definition at line 37 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ HEUR_TIMING

#define HEUR_TIMING SCIP_HEURTIMING_AFTERNODE

Definition at line 38 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 39 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 41 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 42 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 43 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 44 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 45 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 46 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 47 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_USELPROWS

#define DEFAULT_USELPROWS

Value:

FALSE /* should subproblem be created out of the rows in the LP rows,

* otherwise, the copy constructors of the constraints handlers are used */

FALSE

#define FALSE

Definition: def.h:64

Definition at line 48 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_COPYCUTS

#define DEFAULT_COPYCUTS

Value:

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 */

TRUE

#define TRUE

Definition: def.h:63

Definition at line 50 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 52 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 53 of file heur_mutation.c.

Referenced by SCIPincludeHeurMutation().

◆ DEFAULT_RANDSEED

#define DEFAULT_RANDSEED 19 /* initial random seed */

Definition at line 54 of file heur_mutation.c.

Referenced by SCIP_DECL_HEURINIT().

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

scip	original SCIP data structure
fixedvars	array to store the variables that should be fixed in the subproblem
fixedvals	array to store the fixing values to fix variables in the subproblem
nfixedvars	pointer to store the number of variables that should be fixed
minfixingrate	percentage of integer variables that have to be fixed
randnumgen	random number generator
success	used to store whether the creation of the subproblem worked

Definition at line 86 of file heur_mutation.c.

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

Referenced by SCIP_DECL_HEUREXEC().

◆ createNewSol()

static SCIP_RETCODE createNewSol	(	SCIP *	scip,
		SCIP *	subscip,
		SCIP_VAR **	subvars,
		SCIP_HEUR *	heur,
		SCIP_SOL *	subsol,
		SCIP_Bool *	success
	)

static

creates a new solution for the original problem by copying the solution of the subproblem

Parameters

scip	original SCIP data structure
subscip	SCIP structure of the subproblem
subvars	the variables of the subproblem
heur	mutation heuristic structure
subsol	solution of the subproblem
success	used to store whether new solution was found or not

Definition at line 168 of file heur_mutation.c.

References FALSE, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcreateSol(), SCIPfreeBufferArray, SCIPgetNOrigVars(), SCIPgetSolVals(), SCIPgetVarsData(), SCIPsetSolVals(), SCIPtrySolFree(), and TRUE.

Referenced by setupAndSolveSubscipMutation().

◆ 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

scip	SCIP data structure
subscip	sub-SCIP data structure
heur	mutation heuristic
fixedvars	array to store the variables that should be fixed in the subproblem
fixedvals	array to store the fixing values to fix variables in the subproblem
nfixedvars	the number of variables that should be fixed
nsubnodes	node limit for the subproblem
result	pointer to store the result

Definition at line 213 of file heur_mutation.c.

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

Referenced by SCIP_DECL_HEUREXEC().

◆ SCIP_DECL_HEURCOPY()

static SCIP_DECL_HEURCOPY ( heurCopyMutation )

static

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

Definition at line 402 of file heur_mutation.c.

References HEUR_NAME, SCIP_CALL, SCIP_OKAY, SCIPheurGetName(), and SCIPincludeHeurMutation().

◆ 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 416 of file heur_mutation.c.

References SCIP_OKAY, SCIPfreeBlockMemory, SCIPheurGetData(), and SCIPheurSetData().

◆ SCIP_DECL_HEURINIT()

static SCIP_DECL_HEURINIT ( heurInitMutation )

static

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

Definition at line 436 of file heur_mutation.c.

References DEFAULT_RANDSEED, SCIP_CALL, SCIP_OKAY, SCIPcreateRandom(), and SCIPheurGetData().

◆ SCIP_DECL_HEUREXIT()

static SCIP_DECL_HEUREXIT ( heurExitMutation )

static

deinitialization method of primal heuristic

Definition at line 459 of file heur_mutation.c.

References SCIP_OKAY, SCIPfreeRandom(), and SCIPheurGetData().

◆ SCIP_DECL_HEUREXEC()

static SCIP_DECL_HEUREXEC ( heurExecMutation )

static

execution method of primal heuristic

Definition at line 478 of file heur_mutation.c.

References determineVariableFixings(), SCIP_Bool, SCIP_CALL, SCIP_DELAYED, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_Longint, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcheckCopyLimits(), SCIPcreate(), SCIPdebugMsg, SCIPfree(), SCIPfreeBufferArray, SCIPgetBestSol(), SCIPgetNNodes(), SCIPgetNSols(), SCIPgetSolNodenum(), SCIPgetVarsData(), SCIPheurGetData(), SCIPheurGetNBestSolsFound(), SCIPheurGetNCalls(), SCIPisStopped(), SCIPsolIsOriginal(), and setupAndSolveSubscipMutation().

SCIP

Detailed Description

Macros

Functions

Macro Definition Documentation

◆ HEUR_NAME

◆ HEUR_DESC

◆ HEUR_DISPCHAR

◆ HEUR_PRIORITY

◆ HEUR_FREQ

◆ HEUR_FREQOFS

◆ HEUR_MAXDEPTH

◆ HEUR_TIMING

◆ HEUR_USESSUBSCIP

◆ DEFAULT_NODESOFS

◆ DEFAULT_MAXNODES

◆ DEFAULT_MINIMPROVE

◆ DEFAULT_MINNODES

◆ DEFAULT_MINFIXINGRATE

◆ DEFAULT_NODESQUOT

◆ DEFAULT_NWAITINGNODES

◆ DEFAULT_USELPROWS

◆ DEFAULT_COPYCUTS

◆ DEFAULT_BESTSOLLIMIT

◆ DEFAULT_USEUCT

◆ DEFAULT_RANDSEED

Function Documentation

◆ determineVariableFixings()

◆ createNewSol()

◆ setupAndSolveSubscipMutation()

◆ SCIP_DECL_HEURCOPY()

◆ SCIP_DECL_HEURFREE()

◆ SCIP_DECL_HEURINIT()

◆ SCIP_DECL_HEUREXIT()

◆ SCIP_DECL_HEUREXEC()