Cutting stock code for gurobi + python
This code solves the following cutting stock model:
Master problem:
min \sum_{p in P} x_p
s.t. \sum_{p in P} patterns_{ip} * x_p ≥ d_i, for i in I
x_p ≥ 0 and integer, for p in P
Subproblem:
min 1 - \sum_{i in I} price_i * use_i
s.t. \sum_{i in I} w_i * use_i ≤ W_roll
use_i ≥ 0 and integer, for i in I
x_p: number of times pattern p is used
price_i: dual of constraint i in the master problem
use_i: number of item i's in a new pattern
cutstock_grb.py is the code file.
All other files (.log and .lp) are generated by cutstock_grb.py.