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Re: how to get any element from a set
Posted: Tue Apr 04, 2017 5:54 pm
by Manassaldi
Hi,
For example, if yours variable is H(A) the first element corresponds to H('a1')
Bye
Re: how to get any element from a set
Posted: Wed Apr 05, 2017 9:10 am
by Renger
Hi
If you want a specific set element, you can also use the ord and card functions:
Code: Select all
set
A/a1,a2/;
parameter h(a);
* first element
h("a1")
h(a)$(ord(a) = 1)
* second element
h("a2")
h(a)$(ord(a) = 2)
* last element
h(a)$(ord(a) eq card(a))
Cheers
Renger
Re: how to get any element from a set
Posted: Wed Apr 05, 2017 7:53 pm
by cladelpino
Does GAMS not distinguish capital and lower letters?
True. It does not.
To "populate" a set:
Code: Select all
set A /a1,a2/;
set B(A);
B(A)=YES$(ord(A)=2);
display B;
Re: how to get any element from a set
Posted: Tue Jul 23, 2019 5:51 pm
by cardyn
Hi Renger,
when I assign an element of a parameter to a scalar, error happens with "Uncontrolled set entered as constant" and "Set for 'ord' is not controlled"
Set A /a1,a2/;
parameter h(a) /a1*a2 2/;
scalar y /0/;
y=h(a)$(ord(a) = 1);
Could you please tell where the problem is? Thank you.
Best regards,
Yongning
Renger wrote: ↑7 years ago
Hi
If you want a specific set element, you can also use the ord and card functions:
Code: Select all
set
A/a1,a2/;
parameter h(a);
* first element
h("a1")
h(a)$(ord(a) = 1)
* second element
h("a2")
h(a)$(ord(a) = 2)
* last element
h(a)$(ord(a) eq card(a))
Cheers
Renger
Re: how to get any element from a set
Posted: Wed Jul 24, 2019 7:50 am
by Renger
Hi
y is defined as a scalar, so no index. If you write it like you did, Gams expects a set indicator also on the RHS. But this might not what you want, as you set the values for y for all other elements of a to zero:
Code: Select all
parameter y(a);
y(a)$(ord(a) =1) = h(a);
display y(a)
You could keep y as a scalar and write the following
or
Hope this helps
Cheers
Renger