Merging set elements from several GDX files into one basic set

FAQs GAMS
1

How do I merge set elements from several GDX files into one basic set?

2

Below is an example, which shows how to do this, even if the GDX files contain lots of common elements.

First we generate some GDX files:

set a /a,b,c/;
set b /c,d,e/;
$gdxout seta.gdx
$unload a
$gdxout setb.gdx
$unload b
$gdxout

Now we combine these GDX files into one:

set c;
$onmulti
$gdxin seta
$load c=a
$gdxin setb
$load c=b
display c;

which gives us in the lst file:

[...]
 -- LOAD  c = 1:a
[...]
--- MERGE c = 1:b
[...]
----     15 SET c  

a,    b,    c,    d,    e