"TypeError: unsupported operand type(s) for -: 'LessThan' and 'NoneType' " while using sympy equation

回答済み

Varun Deshpande

2021年02月04日 15:16

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addConstr does not seem to accept a sympy inequalty. If this does not work, then how get variables and constraints input from a user and then add them to a model?

m = gp.Model()

decsn_var = [x', 'y']

for i in range(n_decsn):
decsn_var[i] = sym.sympify(decsn_var[i])

for i in range(n_decsn):
decsn_var[i] = m.addVar(lb = -gp.GRB.INFINITY, ub = gp.GRB.INFINITY)

ineq_lower = ['1-x+y', 'y']
for i in range(n_ineq_lower):
  ineq_lower[i] = sym.sympify(ineq_lower[i])

g = ineq_lower[0] <= 0

m.addConstr(g)

TypeError                                 Traceback (most recent call last)
<ipython-input-58-4a83b28d925b> in <module>
----> 1 m.addConstr(g)

src\gurobipy\model.pxi in gurobipy.gurobipy.Model.addConstr()

TypeError: unsupported operand type(s) for -: 'LessThan' and 'NoneType'

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  Simranjit Kaur

  • Gurobi Staff

  2025年06月23日 03:00 編集済み

  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?.
• 

  Silke Horn

  • Gurobi Staff

  2021年02月05日 09:50

  You are right that gurobipy does not support sympy inequalities. Instead you should add your constraints (and variables) as follows:

  x = m.addVar(lb = -gp.GRB.INFINITY, name="x")
  y = m.addVar(lb = -gp.GRB.INFINITY, name="y")
  
  m.addConstr(1-x+y <= 0)

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