How can I count the zero number in my decsion variable?

Awaiting user input

Tangzhe Chen

October 26, 2022 21:44

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I want to count how many zeros in hire[], and get num_hire for the numbers of zero, so I tried to use the following code. But bug come out. How can I count them?

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 16, 2025 23:26

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  Jonasz Staszek

  • Community Moderator

  October 28, 2022 10:12

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  Dear Tangzhe,

  based on the description you provided it is difficult to give specific advice. Could you please share a minimal reproducible example of your problem?

  Best regards
  Jonasz

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  Tangzhe Chen

  October 28, 2022 11:25

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  hire[j] is a decision variable for how many workers are hired in j month in a year in my code. and num_hire, I would like to treat it as a label, counting how many times for the company hire worker in a year. For example, if hire[j]=[0,0,0,0,0,1,2,3,4,5,6,7] in a year (j represents the month) (the company hire 1 person in June and 7 people in Dec. etc.) then the variable num_hire should be 7,cause the company hire people 7 times in this year.

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  Tangzhe Chen

  October 28, 2022 11:28

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  Here is how I define the decision variable Hire[j]  Besides, J is the month in a year 
  

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  Jonasz Staszek

  • Community Moderator

  October 28, 2022 13:12

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  Thanks for these clarifications. In the future please paste the code rather than the screenshot - you can't really copy anything out from a picture...

  My understanding is that you would be interested in knowing how many variables were assigned a value of 0 in the optimal solution to your problem. This can be done by checking the parameter x of the respective variable.

  In your case, the simplified code (not accounting for integer tolerances) would look something like:

  num_hire = 0
  for j in J:
      if hire[j].X == 0:
          num_hire += 1

  If that's not what you're looking for, we would require a complete description of the model you are trying to implement to give further guidance.

  Best regards
  Jonasz

   

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