Can we change the linear expression's lines randomly in gurobi ??

Answered

Jacob Jin

• August 29, 2022 07:57

 

lin_exp_2 = K * sum(
    z_dual[i, l].x * model.getVarByName('z_' + str(i) + '_' + str(l)) for l in L for i in range(N + 1))
+ K * sum(r_dual[i, j].x * model.getVarByName('r_' + str(i) + '_' + str(j)) for j in range(N+1) for i in range(N+1))

If I use the expression above, the expression will not include the last line. 

lin_exp_2 = K * sum(
    z_dual[i, l].x * model.getVarByName('z_' + str(i) + '_' + str(l)) for l in L for i in range(N + 1)) + K * sum(r_dual[i, j].x * model.getVarByName('r_' + str(i) + '_' + str(j)) for j in range(N+1) for i in range(N+1))

The expression above is correct.

Why would that happen?

0

• 

  Jaromił Najman

  Gurobi Staff

  • August 29, 2022 08:32
  • Edited

  It is quite hard to help here, because the snippets you provided are not reproducible.

  I would guess that it some identation + editor issue which is not correctly displayed. You should try using a backslash when you want to write multi line expressions in Python.

  lin_exp_2 = K * sum(
      z_dual[i, l].x * model.getVarByName('z_' + str(i) + '_' + str(l)) for l in L for i in range(N + 1)) \
  + K * sum(r_dual[i, j].x * model.getVarByName('r_' + str(i) + '_' + str(j)) for j in range(N+1) for i in range(N+1))

  If this does not help, you can always use parentheses to make sure that the whole expression is used instead of putting it into 1 long line.

  0

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