/** creates variable */
SCIP_RETCODE SCIPcreateVarBinpacking(
SCIP* scip, /**< SCIP data structure */
SCIP_VAR** var, /**< pointer to variable object */
const char* name, /**< name of variable, or NULL for automatic name creation */
SCIP_Real obj, /**< objective function value */
SCIP_Bool initial, /**< should var's column be present in the initial root LP? */
SCIP_Bool removable, /**< is var's column removable from the LP (due to aging or cleanup)? */
SCIP_VARDATA* vardata /**< user data for this specific variable */
)
{
assert(scip != NULL);
assert(var != NULL);
/* create a basic variable object */
SCIP_CALL( SCIPcreateVarBasic(scip, var, name, 0.0, 1.0, obj, SCIP_VARTYPE_BINARY) );
assert(*var != NULL);
/* set callback functions */
SCIPvarSetData(*var, vardata);
SCIPvarSetDeltransData(*var, vardataDelTrans);
/* set initial and removable flag */
SCIP_CALL( SCIPvarSetInitial(*var, initial) );
SCIP_CALL( SCIPvarSetRemovable(*var, removable) );
SCIPvarMarkDeletable(*var);
SCIPdebug( SCIPprintVar(scip, *var, NULL) );
return SCIP_OKAY;
}
/** execution method of event handler */
static
SCIP_DECL_EVENTEXEC(eventExecProbdatavardeleted)
{
SCIP_VAR* var;
SCIP_PROBDATA* probdata;
int idx;
assert(SCIPeventGetType(event) == SCIP_EVENTTYPE_VARDELETED);
var = SCIPeventGetVar(event);
probdata = (SCIP_PROBDATA*) eventdata;
assert(probdata != NULL);
assert(var != NULL);
/* get index of variable in stablesets array */
idx = (int)(size_t) SCIPvarGetData(var);
SCIPdebugMessage("remove variable %s [%d] from list of stable sets\n", SCIPvarGetName(var), idx);
assert(probdata->stablesetvars[idx] == var);
/* remove variable from stablesets array and release it */
SCIPfreeBlockMemoryArray(scip, &(probdata->stablesets[idx]), probdata->stablesetlengths[idx]); /*lint !e866*/
SCIP_CALL( SCIPreleaseVar(scip, &(probdata->stablesetvars[idx])) );
/* move all subsequent variables to the front */
for( ; idx < probdata->nstablesets - 1; idx++)
{
probdata->stablesets[idx] = probdata->stablesets[idx + 1];
probdata->stablesetlengths[idx] = probdata->stablesetlengths[idx + 1];
probdata->stablesetvars[idx] = probdata->stablesetvars[idx + 1];
SCIPvarSetData(probdata->stablesetvars[idx], (SCIP_VARDATA*) (size_t) idx); /*lint !e571*/
}
probdata->nstablesets--;
return SCIP_OKAY;
}/*lint !e715*/
/** create initial columns */
static
SCIP_RETCODE createInitialColumns(
SCIP* scip, /**< SCIP data structure */
SCIP_PROBDATA* probdata /**< problem data */
)
{
SCIP_CONS** conss;
SCIP_VARDATA* vardata;
SCIP_VAR* var;
char name[SCIP_MAXSTRLEN];
int* ids;
SCIP_Longint* weights;
int nitems;
int i;
conss = probdata->conss;
ids = probdata->ids;
weights = probdata->weights;
nitems = probdata->nitems;
/* create start solution each item in exactly one bin */
for( i = 0; i < nitems; ++i )
{
(void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "item_%d", ids[i]);
SCIPdebugMessage("create variable for item %d with weight = %"SCIP_LONGINT_FORMAT"\n", ids[i], weights[i]);
/* create variable for the packing pattern which contains only this item */
SCIP_CALL( SCIPcreateVarBinpacking(scip, &var, name, 1.0, TRUE, TRUE, NULL) );
/* add variable to the problem */
SCIP_CALL( SCIPaddVar(scip, var) );
/* store variable in the problme data */
SCIP_CALL( SCIPprobdataAddVar(scip, probdata, var) );
/* add variable to corresponding set covering constraint */
SCIP_CALL( SCIPaddCoefSetppc(scip, conss[i], var) );
/* create the variable data for the variable; the variable data contains the information in which constraints the
* variable appears */
SCIP_CALL( SCIPvardataCreateBinpacking(scip, &vardata, &i, 1) );
/* add the variable data to the variable */
SCIPvarSetData(var, vardata);
/* change the upper bound of the binary variable to lazy since the upper bound is already enforced
* due to the objective function the set covering constraint;
* The reason for doing is that, is to avoid the bound of x <= 1 in the LP relaxation since this bound
* constraint would produce a dual variable which might have a positive reduced cost
*/
SCIP_CALL( SCIPchgVarUbLazy(scip, var, 1.0) );
/* release variable */
SCIP_CALL( SCIPreleaseVar(scip, &var) );
}
return SCIP_OKAY;
}
