CODEWITHSUNDEEP
gams-math
yaodao vang
yaodao vang

Reputation: 298

How to find in vector ( parameter)?

If I have a set and parameter

Set A/a1,a9/;
Parameter T(A);

*Suppose p is  T(A)=121311332
 T(A) /1 1,2 2,3 1,4 3,5 1,6 1,7 3,8 3,9 2/;

How to find the third one and changed it to 4?

 (E.g. 121311332 changed to 121341332)

Generally How may I get the nth repetitive element (1,2or 3) from set A and change it?Is there anyway to do that?

Upvotes: 0

Views: 92

Answers (1)

Lutz
Lutz

Reputation: 2292

Edit after clarification in comments:

To change the third occurrence of 1 to 4 you can do this:

Set A          /a1*a9/;
Parameter T(A) /a1 1,a2 2,a3 1,a4 3,a5 1,a6 1,a7 3,a8 3,a9 2/;
Scalar oneCnt  / 0 /;
Display T;

loop(A,
  if(T(A)=1,
    oneCnt = oneCnt+1;
    if(oneCnt=3,
      T(A)=4;
      break;
    )
  );
);

Display T;

Originally, I thought that the third element should be changed. That could be done like this:

You can use the ord operator (https://www.gams.com/latest/docs/UG_OrderedSets.html#UG_OrderedSets_TheOrdOperator) to do that:

Set A/a1*a9/;
Parameter T(A) /a1 1,a2 2,a3 1,a4 3,a5 1,a6 1,a7 3,a8 3,a9 2/;

Display T;

T(A)$(ord(a)=3) = 4;

Display T;

Upvotes: 1

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