operators allocation routine, to be updated and moved to other directory

dream/simulation/opAss_LPmethod.py

+'''
+Created on 2 Jul 2014
+
+@author: Anna
+'''
+
+from pulp import *
+
+
+def opAss_LP(stationList, PBlist, PBskills):
+    '''
+    classdocs
+    '''
+    machines = stationList.keys()
+        
+    # define LP problem    
+    prob = LpProblem("PBassignment", LpMaximize)
+        
+    # declare variables...binary assignment variables (operator i to machine j)
+    PB_ass = LpVariable.dicts('PB', [(i,j) for i in PBlist 
+                                        for j in machines] , 0, 1, LpBinary)
+        
+    # objective...assignment of PBs to stations with higher WIP...sum of WIP associated with stations where PB is assigned
+    obj1 = [stationList[st]['WIP']*PB_ass[(oper,st)] for oper in PBlist for st in machines]
+    prob += lpSum(obj1)
+        
+    # constraint 1: # operators assigned to a station <= 1
+    for machine in machines:
+        prob += lpSum([PB_ass[(oper,machine)] for oper in PBlist]) <= 1
+        
+    # constraint 2: # machines assigned to an oeprator <= 1
+    for operator in PBlist:
+        prob += lpSum([PB_ass[(operator,machine)] for machine in machines]) <= 1
+            
+    # constraint 3: assign operator that are capable of running a machine
+    skills = {}
+    for mach in machines:
+        for oper in PBlist:
+            if stationList[mach]['stationID'] in PBskills[oper]:
+                skills[(mach,oper)] = 1
+            else:
+                skills[(mach,oper)] = 0
+            prob += lpSum([skills[(mach,oper)]-PB_ass[(oper,mach)]]) >= 0
+            
+    # write the problem data to an .lp file.
+    prob.writeLP("PBassignment.lp") 
+    
+    prob.solve()
+    solution={}
+    for mach in machines:
+        for oper in PBlist:
+                
+            if PB_ass[(oper,mach)].varValue > 0.00001:
+                print 'PB', oper, 'assigned to machine', mach
+                solution[str(oper)]=str(mach)
+    return solution
+def main():
+    
+    # dict with stations to be operated during a shift (only active stations...ID can be the same for 2 machines as it identifies the type of process
+    # WIP can be derived from the buffer upstream the station...when 2 machines operate at a step the WIP will be divided between the two machines
+    stations = {}
+    stations['M1'] = {'stationID':1, 'WIP':1}
+    stations['M2'] = {'stationID':2, 'WIP':1}
+#     stations['M3'] = {'stationID':3, 'WIP':1}
+#     stations['M4'] = {'stationID':4, 'WIP':1}
+#     stations['M5'] = {'stationID':5, 'WIP':1}
+#     stations['M6'] = {'stationID':6, 'WIP':1}
+    
+    # dict with stations' IDs on which an operator can work
+    PBskills = {}
+    PBskills['PB1'] = [1, 2]#, 3]
+    PBskills['PB2'] = [1, 2]#, 3]
+#     PBskills['PB3'] = [4, 5]
+#     PBskills['PB4'] = [2, 4]
+#     PBskills['PB5'] = [1, 2]
+#     PBskills['PB6'] = [2, 3, 4]
+#     PBskills['PB7'] = [5, 6]
+#     PBskills['PB8'] = [5]
+#     PBskills['PB9'] = [6]
+    
+    # list of available PB's 
+#     PBlist = ['PB2', 'PB4', 'PB5', 'PB7']
+    PBlist = ['PB1', 'PB2']
+    
+    opAss_LP(stations, PBlist, PBskills)
+
+    
+if __name__ == '__main__':
+    main()
+    
+    
+        
+        
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