Hello Stefan,
the GLPK help list received the mail copied below.
As the question is about Rglpk and not about GLPK I guess you should be
able to answer it.
The Rglpk_read_file function lacks correct error handling. Therefore the
whole R session will end if an error occurs in the GLPK library.
Please, use glp_error_hook() to define a hook function which will
gracefully handle errors.
I append an example code.
Best regards
Heinrich Schuchardt
On 17.02.2015 13:53, [email protected] wrote:
> Hi
>
> I would like to know if it is possible to read separate .dat and .mod
> files written in the GNU Mathematical Programming Language using the
>
> “Rglpk_read_file” function. The .mod files in the “examples” folder
> include a data section and when the data part is removed R crashes.
>
> If working with separate .dat and .mod files is not currently possible,
> I would like to know if this feature might be added in the future.
>
> Thanks
>
> Kind regards,
>
> Tomas
/***********************************************************************
* This code is part of WinGLPK
*
* Copyright (C) 2010 Xypron ([email protected])
*
* WinGLPK is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GLPK is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
* License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GLPK. If not, see <http://www.gnu.org/licenses/>.
***********************************************************************/
/*
* This example file demonstrates how to safely treat errors when
* calling the glpk library.
*
* It creates a problem and alternativly adds 1 or -1 columns.
* Trying to add -1 columns will cause an error to occur.
*/
#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>
#include "glpk.h"
void errorHook(void *in);
void buildModel(int forceError);
#define INFO struct sinfo
struct sinfo {
char *text;
jmp_buf *env;
};
/*
* This is the main function.
*/
int main(int argc, char** argv) {
int i;
printf("GLPK version: %s\n", glp_version());
for (i = 1; i < 5; i++) {
printf ("\nIteration %d", i);
if (i & 1) {
printf(", error expected to occur.\n");
} else {
printf(", success expected.\n");
}
if (runOptimizer(i)) {
printf("An error has occured.\n");
} else {
printf("Successful execution.\n");
}
}
return (EXIT_SUCCESS);
}
/**
* This function secures calls to glpk with an error hook.
* @param forceError force error if bit 0 = 1
* @return ok code: 1 failure, 2 out of memory
*/
int runOptimizer(int forceError) {
int ret = 0;
INFO *info;
info = (INFO*) malloc(sizeof(INFO));
if (info == NULL) {
return 2;
}
info->env = (jmp_buf *) malloc(sizeof(jmp_buf));
if (info->env == NULL) {
free(info);
return 2;
}
info->text = "This information was passed to the hook function.";
if (setjmp(*(info->env))) {
printf("Post treatment of error.\n");
ret = 1;
} else {
glp_error_hook(errorHook, info);
buildModel(forceError);
}
glp_error_hook(NULL, NULL);
free(info->env);
free(info);
return ret;
}
/**
* Build a model with one column
* @param forceError force error if bit 0 = 1
*/
void buildModel(int forceError) {
glp_prob *lp;
/* create problem */
lp = glp_create_prob();
if (forceError & 1) {
/* add -1 column
* this will cause an error.
*/
glp_add_cols(lp, -1);
} else {
/* add 1 column */
glp_add_cols(lp, 1);
}
/* delete problem */
glp_delete_prob(lp);
}
/**
* This hook function will be called if an error occured when
* calling the glpk library
*/
void errorHook(void *in) {
INFO *info;
info = (INFO *) in;
printf("%s\n",info->text);
/* free glpk memory */
glp_free_env();
/* safely return */
longjmp(info->env, 1);
}_______________________________________________
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