How to use if and elif on checking variables?

回答済み

Han Shih

2019年09月22日 20:50

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Dear Python/Gurobi professionals:

Can you help meva question?

If I have two variable,  AA[I,J] and BB[I,J,K]   where I, J, K are index for demensions

How can I check if v.varName= AA[I,J] or v.varName=BB[I,J,K] so I can print as below?

for v in m.getVars():
   if v.varName = AA ???:

       print(AA"))
   elif v.varName = BB ???: 

       print("BB")

 

Thank you very much

Robert

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• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2024年12月06日 00:53

  This post is more than three years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum. Or why not try our AI Gurobot?.
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  Eli Towle

  • Gurobi Staff

  2019年09月23日 17:34

  Hi Robert,

  Assuming you want to look for variables whose names start with these letters, you can use the following:

  for v in m.getVars():
      if v.varName.startswith("AA"):
          print("AA")
      elif v.varName.startswith("BB"):
          print("BB")

  However, it's usually possible to avoid searching for variables by name. This can be done by creating a variable from the object returned by the addVar() or addVars() method. For example,

  aa = m.addVars(5, 5, name="AA")

  creates 25 variables with names AA[0,0], AA[0,1], ..., AA[4,4]. In this example, aa is a tupledict object that contains these variables. This object is very useful, because it allows you direct access to the set of "AA" variables:

  for v in aa:
      print(v.varName)

  Thus, the aa tupledict object can be used to build constraints, retrieve variable values, etc. I hope this helps!

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  Han Shih

  2019年09月23日 17:41

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  Hi Eli,

  Thank you very much. It works!

  Best

  Robert

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  Han Shih

  2019年09月25日 16:10

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  Hell Eli,

  Can you please help me another question?

  I have a code as below:

  for v in m.getVars():
       print('%s %g' % (v.varName, v.x))
  
  

  The varName is 3 by 2 dimension, so x is 3 by 2 dimension too

  When I print, its output is like the following

  A[1,1] 1
  A[1,2] 3
  A[2,1] 2
  A[2,2] 4
  A[3,1] 5
  A[3,2] 3

  is there any way to print a line for each row, like as below:?

  A[1,1] 1   A[1,2] 3
  A[2,1] 2   A[2,2] 4
  A[3,1] 5   A[3,2] 3

  Thank you very much

  Robert

   

   

   

   

   

   

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  Eli Towle

  • Gurobi Staff

  2019年09月25日 22:53

  Hi Robert,

  Assuming your decision variables were added in the following manner:

  A = m.addVars(range(1,4), range(1,3), name="A")

  you can print a line for each row as follows:

  for i in range(1, 4):
      alist = ["%s %g" % (v.varName, v.X) for v in A.select(i, '*')]
      print("\t".join(alist))

  This code snippet uses the select() method of the tupledict object, as well as a Python list comprehension. An example of the output:

  A[1,1] 1        A[1,2] 3   
  A[2,1] 2        A[2,2] 4   
  A[3,1] 5        A[3,2] 3   

  I hope this helps!

  Eli

   

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  Han Shih

  2019年09月26日 00:35

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  Hi Eli,

  Thank you very much for your help. It seems not easy to write the codes. I will give a try.

  Sincerely,

  Robert

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