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Transport7.java
1package com.gams.examples.transport;
2
3import java.io.File;
4
5import com.gams.api.GAMSCheckpoint;
6import com.gams.api.GAMSGlobals;
7import com.gams.api.GAMSJob;
8import com.gams.api.GAMSModelInstance;
9import com.gams.api.GAMSModifier;
10import com.gams.api.GAMSOptions;
11import com.gams.api.GAMSParameter;
12import com.gams.api.GAMSSetRecord;
13import com.gams.api.GAMSVariable;
14import com.gams.api.GAMSWorkspace;
15import com.gams.api.GAMSWorkspaceInfo;
16
23public class Transport7 {
24
25 public static void main(String[] args) {
26 // check workspace info from command line arguments
27 GAMSWorkspaceInfo wsInfo = new GAMSWorkspaceInfo();
28 if (args.length > 0)
29 wsInfo.setSystemDirectory( args[0] );
30 // create a directory
31 File workingDirectory = new File(System.getProperty("user.dir"), "Transport7");
32 workingDirectory.mkdir();
33 wsInfo.setWorkingDirectory(workingDirectory.getAbsolutePath());
34 // create a workspace
35 GAMSWorkspace ws = new GAMSWorkspace(wsInfo);
36 // create a checkpoint
37 GAMSCheckpoint cp = ws.addCheckpoint();
38
39 // initialize a checkpoint by running a job
40 GAMSJob t7 = ws.addJobFromString(model);
41 t7.run(cp);
42
43 // create a MoelInstance and solve it multiple times with different scalar bmult
44 GAMSModelInstance mi = cp.addModelInstance();
45 GAMSParameter bmult = mi.SyncDB().addParameter("bmult", "demand multiplier");
46 GAMSOptions opt = ws.addOptions();
47 opt.setAllModelTypes("cplex");
48
49 // instantiate the ModelInstance and pass a model definition and Modifier to declare bmult mutable
50 mi.instantiate("transport use lp min z", opt, new GAMSModifier(bmult));
51
52 bmult.addRecord().setValue( 1.0 );
53 double[] bmultlist = new double[] { 0.6, 0.7 , 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 };
54
55 for (double b : bmultlist) {
56 bmult.getFirstRecord().setValue( b );
57 mi.solve();
58 System.out.println("Scenario bmult=" + b + ":");
59 System.out.println(" Modelstatus: " + mi.getModelStatus());
60 System.out.println(" Solvestatus: " + mi.getSolveStatus());
61 System.out.println(" Obj: " + mi.SyncDB().getVariable("z").findRecord().getLevel());
62 }
63
64 // create a ModelInstance and solve it with single links in the network blocked
65 mi = cp.addModelInstance();
66
67 GAMSVariable x = mi.SyncDB().addVariable("x", 2, GAMSGlobals.VarType.POSITIVE, "");
68 GAMSParameter xup = mi.SyncDB().addParameter("xup", 2, "upper bound on x");
69
70 // instantiate the ModelInstance and pass a model definition and Modifier to declare upper bound of X mutable
71 mi.instantiate("transport use lp min z", new GAMSModifier(x, GAMSGlobals.UpdateAction.UPPER, xup));
72
73 for (GAMSSetRecord i : t7.OutDB().getSet("i")) {
74 for (GAMSSetRecord j : t7.OutDB().getSet("j")) {
75 xup.clear();
76 String[] keys = { i.getKey(0), j.getKey(0) };
77 xup.addRecord(keys).setValue(0);
78 mi.solve();
79 System.out.println("Scenario link blocked: " + i.getKey(0) + " - " + j.getKey(0));
80 System.out.println(" Modelstatus: " + mi.getModelStatus());
81 System.out.println(" Solvestatus: " + mi.getSolveStatus());
82 System.out.println(" Obj: " + mi.SyncDB().getVariable("z").findRecord().getLevel());
83 }
84 }
85 }
86
87
88 static String model =
89 "Sets \n" +
90 " i canning plants / seattle, san-diego / \n" +
91 " j markets / new-york, chicago, topeka / ; \n" +
92 " \n" +
93 "Parameters \n" +
94 " a(i) capacity of plant i in cases \n" +
95 " / seattle 350 \n" +
96 " san-diego 600 / \n" +
97 " \n" +
98 " b(j) demand at market j in cases \n" +
99 " / new-york 325 \n" +
100 " chicago 300 \n" +
101 " topeka 275 / ; \n" +
102 " \n" +
103 "Table d(i,j) distance in thousands of miles \n" +
104 " new-york chicago topeka \n" +
105 "seattle 2.5 1.7 1.8 \n" +
106 "san-diego 2.5 1.8 1.4 ; \n" +
107 " \n" +
108 "Scalar f freight in dollars per case per thousand miles /90/ ; \n" +
109 "Scalar bmult demand multiplier /1/; \n" +
110 " \n" +
111 "Parameter c(i,j) transport cost in thousands of dollars per case ; \n" +
112 " c(i,j) = f * d(i,j) / 1000 ; \n" +
113 " \n" +
114 "Variables \n" +
115 " x(i,j) shipment quantities in cases \n" +
116 " z total transportation costs in thousands of dollars ; \n" +
117 " \n" +
118 "Positive Variable x ; \n" +
119 " \n" +
120 "Equations \n" +
121 " cost define objective function \n" +
122 " supply(i) observe supply limit at plant i \n" +
123 " demand(j) satisfy demand at market j ; \n" +
124 " \n" +
125 " cost .. z =e= sum((i,j), c(i,j)*x(i,j)) ; \n" +
126 " \n" +
127 " supply(i) .. sum(j, x(i,j)) =l= a(i) ; \n" +
128 " \n" +
129 " demand(j) .. sum(i, x(i,j)) =g= bmult*b(j) ; \n" +
130 " \n" +
131 "Model transport /all/ ; \n" +
132 " \n";
133}
com::gams::api::GAMSCheckpoint::addModelInstance
GAMSModelInstance addModelInstance()
com::gams::api::GAMSDatabase::addVariable
GAMSVariable addVariable(String identifier, int dimension, GAMSGlobals.VarType varType)
com::gams::api::GAMSDatabase::addParameter
GAMSParameter addParameter(String identifier, int dimension)
com::gams::api::GAMSDatabase::getVariable
GAMSVariable getVariable(String identifier)
com::gams::api::GAMSDatabase::getSet
GAMSSet getSet(String identifier)
com::gams::api::GAMSJob::OutDB
GAMSDatabase OutDB()
com::gams::api::GAMSModelInstance::getModelStatus
GAMSGlobals.ModelStat getModelStatus()
com::gams::api::GAMSModelInstance::getSolveStatus
GAMSGlobals.SolveStat getSolveStatus()
com::gams::api::GAMSModelInstance::instantiate
void instantiate(String modelDefinition, GAMSModifier ... modifiers)
com::gams::api::GAMSOptions::setAllModelTypes
void setAllModelTypes(String value)
com::gams::api::GAMSSymbol::findRecord
T findRecord(String ... keys)
com::gams::api::GAMSSymbol::addRecord
T addRecord(Vector< String > keys)
com::gams::api::GAMSWorkspaceInfo::setSystemDirectory
void setSystemDirectory(String directory)
com::gams::api::GAMSWorkspaceInfo::setWorkingDirectory
void setWorkingDirectory(String directory)
com::gams::api::GAMSWorkspace::addJobFromString
GAMSJob addJobFromString(String source)
com::gams::api::GAMSWorkspace::addCheckpoint
GAMSCheckpoint addCheckpoint()
com::gams.examples.transport.Transport7
This example shows how to create a GAMSModelInstance from a GAMSCheckpoint and how to modify a parame...
Definition: Transport7.java:23
com::gams
Provides package namespace for Java interface and examples to General Algebraic Model System (GAMS).
com
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