117 lines
3.5 KiB
Python
117 lines
3.5 KiB
Python
from ortools.sat.python import cp_model
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def SolveRosteringWithTravel():
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model = cp_model.CpModel()
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# [duration, start, end, location]
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jobs = [[3, 0, 6, 1], [5, 0, 6, 0], [1, 3, 7, 1], [1, 3, 5, 0], [3, 0, 3, 0],
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[3, 0, 8, 0]]
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max_length = 20
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num_machines = 3
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all_machines = range(num_machines)
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horizon = 20
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travel_time = 1
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num_jobs = len(jobs)
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all_jobs = range(num_jobs)
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intervals = []
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optional_intervals = []
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performed = []
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starts = []
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ends = []
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travels = []
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for m in all_machines:
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optional_intervals.append([])
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for i in all_jobs:
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# Create main interval.
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start = model.NewIntVar(jobs[i][1], horizon, 'start_%i' % i)
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duration = jobs[i][0]
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end = model.NewIntVar(0, jobs[i][2], 'end_%i' % i)
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interval = model.NewIntervalVar(start, duration, end, 'interval_%i' % i)
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starts.append(start)
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intervals.append(interval)
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ends.append(end)
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job_performed = []
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job_travels = []
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for m in all_machines:
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performed_on_m = model.NewBoolVar('perform_%i_on_m%i' % (i, m))
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job_performed.append(performed_on_m)
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# Create an optional copy of interval to be executed on a machine
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location0 = model.NewIntVar(
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jobs[i][3], jobs[i][3], 'location_%i_on_m%i' % (i, m))
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start0 = model.NewIntVar(jobs[i][1], horizon, 'start_%i_on_m%i' % (i, m))
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end0 = model.NewIntVar(0, jobs[i][2], 'end_%i_on_m%i' % (i, m))
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interval0 = model.NewOptionalIntervalVar(
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start0, duration, end0, performed_on_m, 'interval_%i_on_m%i' % (i, m))
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optional_intervals[m].append(interval0)
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# We only propagate the constraint if the tasks is performed on the machine.
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model.Add(start0 == start).OnlyEnforceIf(performed_on_m)
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# Adding travel constraint
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travel = model.NewBoolVar('is_travel_%i_on_m%i' % (i, m))
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startT = model.NewIntVar(0, horizon, 'start_%i_on_m%i' % (i, m))
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endT = model.NewIntVar(0, horizon, 'end_%i_on_m%i' % (i, m))
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intervalT = model.NewOptionalIntervalVar(
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startT, travel_time, endT, travel,
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'travel_interval_%i_on_m%i' % (i, m))
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optional_intervals[m].append(intervalT)
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job_travels.append(travel)
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model.Add(end0 == startT).OnlyEnforceIf(travel)
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performed.append(job_performed)
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travels.append(job_travels)
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model.Add(sum(job_performed) == 1)
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for m in all_machines:
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if m == 1:
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for i in all_jobs:
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if i == 2:
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for c in all_jobs:
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if (i != c) and (jobs[i][3] != jobs[c][3]):
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is_job_earlier = model.NewBoolVar('is_j%i_earlier_j%i' % (i, c))
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model.Add(starts[i] < starts[c]).OnlyEnforceIf(is_job_earlier)
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model.Add(starts[i] >= starts[c]).OnlyEnforceIf(
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is_job_earlier.Not())
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# Max Length constraint (modeled as a cumulative)
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# model.AddCumulative(intervals, demands, max_length)
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# Choose which machine to perform the jobs on.
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for m in all_machines:
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model.AddNoOverlap(optional_intervals[m])
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# Objective variable.
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total_cost = model.NewIntVar(0, 1000, 'cost')
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model.Add(total_cost == sum(
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performed[j][m] * (10 * (m + 1)) for j in all_jobs for m in all_machines))
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model.Minimize(total_cost)
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# Solve model.
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solver = cp_model.CpSolver()
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result = solver.Solve(model)
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print()
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print(result)
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print('Statistics')
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print(' - conflicts : %i' % solver.NumConflicts())
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print(' - branches : %i' % solver.NumBranches())
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print(' - wall time : %f ms' % solver.WallTime())
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def main():
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SolveRosteringWithTravel()
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if __name__ == '__main__':
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main()
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