How can I restrict a variable that can only take value in a list？

Ongoing

Morris Lin

• September 16, 2022 09:06

list1=[1,2,3,4];

i want a variable that can only take value in that list

0

• 

  Marika Karbstein

  Gurobi Staff

  • September 16, 2022 09:29

  It is not possible to give an arbitrary list that indicates the allowed values of a variable.
  If your variable is only allowed to take a value 1,2,3, or 4, you could define an integer variable with lower bound 1 and upper bound 4.

  0
• 

  Jonasz Staszek

  Community Moderator

  • September 22, 2022 13:39

  

  

  

  Dear Marika, dear Morris,

  as a workaround, one can try to use indicator variables and constraints to model the desired behaviour (have a look here for an example). This will most likely not scale well though.

  Best regards
  Jonasz

  0
• 

  Morris Lin

  • September 23, 2022 08:41

  

  

  

  Thank for Jonasz's help.

  I have a idea to achieve it. Using indicator variables and limiting x like (0.9999<=x<=1.0001)&(1.9999<=x<=2.0001)...

  There's a similar problem that bothers me. I post it below.

  x only can equal 1 or 2 or 3 or 4

  y only can equal 2 or 3 or 4 or 5，y is related to x. 

  for example, x==1, y==2 or x==2, y==3 or ...

  And I usually code in matlab, it is hard to express the above by martix.

   

   

  0

Please sign in to leave a comment.