using csv2gdx and gdxin

GAMS
1

Hi everyone,

I’m new to GAMS, and this is my first post.

I’m trying to import data from a CSV file. I have these 2 lines of code in my “.gms” file (let’s call them line 1 and line 2 respectively):

execute ‘csv2gdx i.csv output=in_i.gdx index=1 values=1 useheader=y id=i’;
$gdxin in_i.gdx

I get a lot of errors, but I’ll focus on the top-most one (most of the errors are 502 and 510):

*** Error 510 in [my directory name]
Unable to pen gdx file for $GDXIN

I also noticed that if I run the 2 lines in different files, then there are no issues (run line 1 in one “gms” file and then run line 2 in the next “gms” file).

Can anyone help me to understand this issue? I tried inserting a -sleep- command between the 2 lines (thinking that the second line was being run before the first was complete), but that didn’t help. Does GAMS not run the scripts from top to bottom?

best,

Brian

2

Brian,

GAMS is a two pass system with a compilation and an execution phase (see https://www.gams.com/latest/docs/UG_GamsCall.html#UG_GamsCall_TwoPass).
Dollar control options like $gdxin are executed during the compilation phase.
Programs called via execute ‘…’; are executed during the execution phase (see https://www.gams.com/latest/docs/UG_GamsCall.html?search=#UG_ExecutingAnExternalProgram).

Hence, you try to open the gdx file before it is created. You could call csv2gdx during compilation with $call

$call csv2gdx i.csv output=in_i.gdx index=1 values=1 useheader=y id=i

I hope this helps!

Fred

3

That does help. Thanks, Fred.