Re: [Help-glpk] Controlling glpsol output

[Brady Hunsaker]

On Mon, 2004-02-16 at 08:06, Pieter Thysebaert wrote:
> 
> 
> Hello all,
> 
> I'm using glpk 4.2 and am trying to use the standalone solver "glpsol"
> 
> THe problem i'm solving is a MIP.
> 
> For each real-world entity, the decision process must decide on a set of 
> binary variables (i.e. set them to 0 or 1).
> 
> Most of these sets must obey a "sum = 1" constraint.
> 
> Obviously, 
> 1. Most variables are 0 and only a few are 1 in the solution
> 2. I can get all the info I need (read: I am only interested in...) the 
> variables which are set to 1 in the solution
> 
> 
> When using "glpsol --model test.model --output test.output" I get the entire 
> solution;
> 
> Is there a way to control which variables are output?
> 
> Or even better, is there a way to execute a display-like statement after the 
> solution has been found, so that I can limit the output to whatever I want?
> 
> Or do I really have to write an entrie parser for the complete output file in 
> this case?
> 
> 
> Pieter
> 
> 

I think you have two choices:

1. Write a parser for the big output file, as you suggested.

2. Instead of using glpsol, write a small program.  Appendix A of the
Language manual describes how to call the parser with the function
lpx_read_model to input your instance.  Then call the solution function
(lpx_integer, I guess) and use lpx_mip_col_val to determine which
columns you want to display.

But there was a change in API for 4.4; it looks like you should use
lpx_get_mip_col if you're using 4.2.

Brady