new example

examples/python/vendor_scheduling.py

@@ -0,0 +1,103 @@
+from ortools.constraint_solver import pywrapcp
+
+
+def main():
+
+  # Create the solver.
+  solver = pywrapcp.Solver('Vendors scheduling')
+
+  #
+  # data
+  #
+
+  num_vendors = 9
+  num_hours = 10
+  num_work_types = 1
+
+  trafic = [100, 500, 100, 200, 320, 300, 200, 220, 300, 120]
+  max_trafic_per_vendor = 100
+
+  # Last columns are :
+  #   index_of_the_schedule, sum of worked hours (per work type).
+  # The index is useful for branching.
+  possible_schedules = [
+      [1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 8],
+      [1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 4],
+      [0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 2, 5],
+      [0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3, 4],
+      [1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 4, 3],
+      [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0]]
+
+  num_possible_schedules = len(possible_schedules)
+  selected_schedules = []
+  vendors_stat = []
+  hours_stat = []
+
+  #
+  # declare variables
+  #
+  x = {}
+
+  for i in range(num_vendors):
+    tmp = []
+    for j in range(num_hours):
+      x[i, j] = solver.IntVar(0, num_work_types, 'x[%i,%i]' % (i, j))
+      tmp.append(x[i, j])
+    selected_schedule = solver.IntVar(0, num_possible_schedules - 1,
+                                      's[%i]' % i)
+    hours = solver.IntVar(0, num_hours, 'h[%i]' % i)
+    selected_schedules.append(selected_schedule)
+    vendors_stat.append(hours)
+    tmp.append(selected_schedule)
+    tmp.append(hours)
+
+    solver.Add(solver.AllowedAssignments(tmp, possible_schedules))
+
+  #
+  # Statistics and constraints for each hour
+  #
+  for j in range(num_hours):
+    workers = solver.Sum([x[i, j] for i in range(num_vendors)]).Var()
+    hours_stat.append(workers)
+    solver.Add(workers * max_trafic_per_vendor >= trafic[j])
+
+  #
+  # Redundant constraint: sort selected_schedules
+  #
+  for i in range(num_vendors - 1):
+    solver.Add(selected_schedules[i] <= selected_schedules[i + 1])
+
+  #
+  # Search
+  #
+  db = solver.Phase(selected_schedules,
+                    solver.CHOOSE_FIRST_UNBOUND,
+                    solver.ASSIGN_MIN_VALUE)
+
+  solver.NewSearch(db)
+
+  num_solutions = 0
+  while solver.NextSolution():
+    num_solutions += 1
+
+    for i in range(num_vendors):
+      print 'Vendor %i: ' % i, possible_schedules[selected_schedules[i].Value()]
+    print
+
+    print 'Statistics per day:'
+    for j in range(num_hours):
+      print 'Day%2i: ' % j,
+      print hours_stat[j].Value(),
+      print
+    print
+
+  solver.EndSearch()
+  print
+  print 'num_solutions:', num_solutions
+  print 'failures:', solver.Failures()
+  print 'branches:', solver.Branches()
+  print 'WallTime:', solver.WallTime(), 'ms'
+
+
+if __name__ == '__main__':
+  main()