transforming binary gurobi tupledict into np.array

Answered

Lukas Schroth

July 03, 2022 22:28

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Hello,

I formulated a MILP using the gurobi python interface.

In my model i created a tuple dict x of binary Variables with 2d-keys using model.addVars().

For further calculations, I need to transform the resulting tuple dict into a np.array, with x[i][j] beeing the entry in the i-th row and j-th column of the np.array/matrix.

What is the most efficient way to do that? Or should i already choose something different then model.addVars() to begin with?

I am new to Gurobi and I appreciate any help

Yours,

Lukas 

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 16, 2025 23:33

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• 

  Simon Bowly

  • Gurobi Staff

  July 05, 2022 03:21

  Hi Lukas,

  You could write the solution values from the tupledict into a numpy array like so:

  arr = np.zeros((M, N))
  for i in range(M):
      for j in range(N):
          arr[i,j] = x[i,j].X

  But you may find it more convenient to use addMVar instead of addVars. If x is instead stored as an MVar, then retrieving the solution using x.X directly gives you the numpy array you are looking for.

  Best regards,
  Simon

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