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TransportGDX.java
1package com.gams.examples.transport;
2
3import java.io.File;
4import java.util.ArrayList;
5import java.util.Arrays;
6import java.util.HashMap;
7import java.util.List;
8import java.util.Map;
9import java.util.Map.Entry;
10import java.util.Vector;
11
12import com.gams.api.GAMSDatabase;
13import com.gams.api.GAMSParameter;
14import com.gams.api.GAMSParameterRecord;
15import com.gams.api.GAMSSet;
16import com.gams.api.GAMSSetRecord;
17import com.gams.api.GAMSWorkspace;
18import com.gams.api.GAMSWorkspaceInfo;
19
27public class TransportGDX {
28
29 public static void main(String[] args) {
30 // check workspace info from command line arguments
31 GAMSWorkspaceInfo wsInfo = new GAMSWorkspaceInfo();
32 if (args.length > 0)
33 wsInfo.setSystemDirectory( args[0] );
34 // create a directory
35 File workingDirectory = new File(System.getProperty("user.dir"), "TransportGDX");
36 workingDirectory.mkdir();
37 wsInfo.setWorkingDirectory(workingDirectory.getAbsolutePath());
38 // create a workspace
39 GAMSWorkspace ws = new GAMSWorkspace(wsInfo);
40
41 // prepare input data
42 List<String> plants = Arrays.asList("Seattle", "San-Diego");
43 List<String> markets = Arrays.asList("New-York", "Chicago", "Topeka");
44 Map<String, Double> capacity = new HashMap<String, Double>();
45 {
46 capacity.put("Seattle", Double.valueOf(350.0));
47 capacity.put("San-Diego", Double.valueOf(600.0));
48 }
49 Map<String, Double> demand = new HashMap<String, Double>();
50 {
51 demand.put("New-York", Double.valueOf(325.0));
52 demand.put("Chicago", Double.valueOf(300.0));
53 demand.put("Topeka", Double.valueOf(275.0));
54 }
55
56 Map<Vector<String>, Double> distance = new HashMap<Vector<String>, Double>();
57 {
58 distance.put( new Vector<String>( Arrays.asList(new String[]{"Seattle", "New-York"}) ), Double.valueOf(2.5));
59 distance.put( new Vector<String>( Arrays.asList(new String[]{"Seattle", "Chicago"}) ), Double.valueOf(1.7));
60 distance.put( new Vector<String>( Arrays.asList(new String[]{"Seattle", "Topeka"}) ), Double.valueOf(1.8));
61 distance.put( new Vector<String>( Arrays.asList(new String[]{"San-Diego", "New-York"}) ), Double.valueOf(2.5));
62 distance.put( new Vector<String>( Arrays.asList(new String[]{"San-Diego", "Chicago"}) ), Double.valueOf(1.8));
63 distance.put( new Vector<String>( Arrays.asList(new String[]{"San-Diego", "Topeka"}) ), Double.valueOf(1.4));
64 }
65
66 // add database and input data into the database
67 GAMSDatabase db = ws.addDatabase();
68
69 GAMSSet i = db.addSet("i", 1, "canning plants");
70 for(String p : plants)
71 i.addRecord(p);
72
73 GAMSSet j = db.addSet("j", 1, "markets");
74 for(String m : markets)
75 j.addRecord(m);
76
77 GAMSParameter a = db.addParameter("a", "capacity of plant i in cases", i);
78 for (String p : plants) {
79 a.addRecord(p).setValue( capacity.get(p) );
80 }
81
82 GAMSParameter b = db.addParameter("b", "demand at market j in cases", j);
83 for(String m : markets)
84 b.addRecord(m).setValue( demand.get(m) );
85
86 GAMSParameter d = db.addParameter("d", "distance in thousands of miles", i, j);
87 for(Vector<String> vd : distance.keySet())
88 d.addRecord(vd).setValue( distance.get(vd).doubleValue() );
89
90 GAMSParameter f = db.addParameter("f", "freight in dollars per case per thousand miles");
91 f.addRecord().setValue( 90 );
92
93 // export the GAMSDatabase to a GDX file with name 'data.gdx' located in the 'workingDirectory' of the GAMSWorkspace
94 db.export("data.gdx");
95
96 // add a new GAMSDatabase and initialize it from the GDX file just created
97 GAMSDatabase gdxdb = ws.addDatabaseFromGDX("data.gdx");
98
99 // read symbol data from the database and fill them into Java data structures
100 List<String> gdxPlants = new ArrayList<String>();
101 for(GAMSSetRecord rec : gdxdb.getSet("i"))
102 gdxPlants.add(rec.getKey(0));
103
104 List<String> gdxMarkets = new ArrayList<String>();
105 for(GAMSSetRecord rec : gdxdb.getSet("j"))
106 gdxMarkets.add(rec.getKey(0));
107
108 Map<String, Double> gdxCapacity = new HashMap<String, Double>();
109 for(GAMSParameterRecord rec : gdxdb.getParameter("a"))
110 gdxCapacity.put(rec.getKey(0), rec.getValue());
111
112 Map<String, Double> gdxDemand = new HashMap<String, Double>();;
113 for(GAMSParameterRecord rec : gdxdb.getParameter("b"))
114 gdxDemand.put(rec.getKey(0), rec.getValue());
115
116 Map<Vector<String>, Double> gdxDistance = new HashMap<Vector<String>, Double>();
117 for(GAMSParameterRecord rec : gdxdb.getParameter("d"))
118 gdxDistance.put( new Vector<String>( Arrays.asList(new String[]{rec.getKey(0), rec.getKey(1)}) ), rec.getValue());
119
120 double gdxFreight = gdxdb.getParameter("f").getFirstRecord().getValue();
121
122 // print out data read from GDX file
123 System.out.println("Data read from data.gdx");
124 System.out.println ("Set i: " + gdxdb.getSet("i").getText() );
125 for(String p : gdxPlants)
126 System.out.println (" " + p);
127
128 System.out.println ("Set j: "+ gdxdb.getSet("j").getText());
129 for(String m : gdxMarkets)
130 System.out.println (" " + m);
131
132 System.out.println ("Parameter a: "+ gdxdb.getParameter("a").getText());
133 for (Entry<String, Double> aEntry : gdxCapacity.entrySet())
134 System.out.println (" " + aEntry.getKey() + ": " + aEntry.getValue());
135
136 System.out.println ("Parameter b: "+ gdxdb.getParameter("b").getText());
137 for (Entry<String, Double> bEntry : gdxDemand.entrySet())
138 System.out.println (" " + bEntry.getKey() + ": " + bEntry.getValue());
139
140 System.out.println ("Parameter d: " + gdxdb.getParameter("d").getText());
141 for (Entry<Vector<String>, Double> dEntry : gdxDistance.entrySet())
142 System.out.println (" " + dEntry.getKey() + ": " + dEntry.getValue());
143
144 System.out.println ("Scalar f: " + gdxdb.getParameter("f").getText());
145 System.out.println (" " + gdxFreight);
146 }
147}
com::gams::api::GAMSDatabase::getParameter
GAMSParameter getParameter(String identifier)
com::gams::api::GAMSDatabase::addSet
GAMSSet addSet(String identifier, int dimension)
com::gams::api::GAMSDatabase::addParameter
GAMSParameter addParameter(String identifier, int dimension)
com::gams::api::GAMSDatabase::getSet
GAMSSet getSet(String identifier)
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::addDatabaseFromGDX
GAMSDatabase addDatabaseFromGDX(String gdxFileName)
com::gams.examples.transport.TransportGDX
This example shows the use of the GAMSDatabase class for reading and writing GDX files.
Definition: TransportGDX.java:27
com::gams
Provides package namespace for Java interface and examples to General Algebraic Model System (GAMS).
com
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