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CutstockModel.java
1package com.gams.examples.cutstock;
2
3import java.io.PrintStream;
4
5import com.gams.api.GAMSDatabase;
6import com.gams.api.GAMSException;
7import com.gams.api.GAMSJob;
8import com.gams.api.GAMSOptions;
9import com.gams.api.GAMSParameter;
10import com.gams.api.GAMSSet;
11import com.gams.api.GAMSWorkspace;
12
17public class CutstockModel {
18 private GAMSSet fWidths;
19 private GAMSParameter fRawWidth;
20 private GAMSParameter fDemand;
21 private GAMSParameter fWidth;
22 private GAMSParameter fPatRep;
23
24 private GAMSWorkspace fws;
25 private GAMSDatabase fCutstockData, fDbOut;
26 private GAMSOptions fopt;
27 private GAMSJob job;
28
32 public CutstockModel(GAMSWorkspace ws) {
33 fws = ws;
34 fopt = ws.addOptions();
35
36 fCutstockData = ws.addDatabase("gdxincname");
37
38 fopt.defines("gdxincname", "gdxincname");
39 fopt.setSolveLink( GAMSOptions.ESolveLink.LoadLibrary );
40 fopt.defines("dbOut1", "dbOut1");
41
42 fWidths = fCutstockData.addSet("i", "widths");
43 fRawWidth = fCutstockData.addParameter("r", "raw width");
44 fDemand = fCutstockData.addParameter("d", "demand", fWidths);
45 fWidth = fCutstockData.addParameter("w", "width", fWidths);
46
47 job = ws.addJobFromString( this.getModelSource() );
48 }
49
51 public void run() {
52 this.run(null);
53 }
54
58 public void run(PrintStream output) {
59 if (!fCutstockData.checkDomains())
60 throw new GAMSException("Domain Errors in Cutstock Database");
61
62 job.run(fopt, null, output, false, fCutstockData);
63 fDbOut = fws.addDatabaseFromGDX(fopt.getDefinitionOf("dbOut1") + ".gdx");
64 fPatRep = fDbOut.getParameter("patrep");
65 }
66
68 public GAMSSet getWidths() { return fWidths; }
69
71 public GAMSParameter getRawWidth() { return fRawWidth; }
72
74 public GAMSParameter getDemand() { return fDemand; }
75
77 public GAMSParameter getWidth() { return fWidth; }
78
80 public GAMSParameter getPatRep() { return fPatRep; }
81
83 public GAMSOptions getOpt() { return fopt; }
84
86 public String getModelSource() { return model; }
87
88 static String model =
89 "$Title Cutting Stock - A Column Generation Approach (CUTSTOCK,SEQ=294) \n" +
90 " \n" +
91 "$ontext \n" +
92 "The task is to cut out some paper products of different sizes from a \n" +
93 "large raw paper roll, in order to meet a customer's order. The objective \n" +
94 "is to minimize the required number of paper rolls. \n" +
95 " \n" +
96 "P. C. Gilmore and R. E. Gomory, A linear programming approach to the \n" +
97 "cutting stock problem, Part I, Operations Research 9 (1961), 849-859. \n" +
98 " \n" +
99 "P. C. Gilmore and R. E. Gomory, A linear programming approach to the \n" +
100 "cutting stock problem, Part II, Operations Research 11 (1963), 863-888. \n" +
101 "$offtext \n" +
102 " \n" +
103 "Set i widths \n" +
104 "Parameter \n" +
105 " r raw width \n" +
106 " w(i) width \n" +
107 " d(i) demand ; \n" +
108 " \n" +
109 "$if not set gdxincname $abort 'no include file name for data file provided'\n" +
110 "$gdxin %gdxincname% \n" +
111 "$load r i w d \n" +
112 "$gdxin \n" +
113 " \n" +
114 "* Gilmore-Gomory column generation algorithm \n" +
115 " \n" +
116 "Set p possible patterns /p1*p1000/ \n" +
117 " pp(p) dynamic subset of p \n" +
118 "Parameter \n" +
119 " aip(i,p) number of width i in pattern growing in p; \n" +
120 " \n" +
121 "* Master model \n" +
122 "Variable xp(p) patterns used \n" +
123 " z objective variable \n" +
124 "Integer variable xp; xp.up(p) = sum(i, d(i)); \n" +
125 " \n" +
126 "Equation numpat number of patterns used \n" +
127 " demand(i) meet demand; \n" +
128 " \n" +
129 "numpat.. z =e= sum(pp, xp(pp)); \n" +
130 "demand(i).. sum(pp, aip(i,pp)*xp(pp)) =g= d(i); \n" +
131 " \n" +
132 "model master /numpat, demand/; \n" +
133 " \n" +
134 "* Pricing problem - Knapsack model \n" +
135 "Variable y(i) new pattern; \n" +
136 "Integer variable y; y.up(i) = ceil(r/w(i)); \n" +
137 " \n" +
138 "Equation defobj \n" +
139 " knapsack knapsack constraint; \n" +
140 " \n" +
141 "defobj.. z =e= 1 - sum(i, demand.m(i)*y(i)); \n" +
142 "knapsack.. sum(i, w(i)*y(i)) =l= r; \n" +
143 " \n" +
144 "model pricing /defobj, knapsack/; \n" +
145 " \n" +
146 "* Initialization - the initial patterns have a single width \n" +
147 "pp(p) = ord(p)<=card(i); \n" +
148 "aip(i,pp(p))$(ord(i)=ord(p)) = floor(r/w(i)); \n" +
149 "*display aip; \n" +
150 " \n" +
151 "Scalar done loop indicator /0/ \n" +
152 "Set pi(p) set of the last pattern; pi(p) = ord(p)=card(pp)+1; \n" +
153 " \n" +
154 "option optcr=0,limrow=0,limcol=0,solprint=off; \n" +
155 " \n" +
156 "While(not done and card(pp)<card(p), \n" +
157 " solve master using rmip minimizing z; \n" +
158 " solve pricing using mip minimizing z; \n" +
159 " \n" +
160 "* pattern that might improve the master model found? \n" +
161 " if(z.l < -0.001, \n" +
162 " aip(i,pi) = round(y.l(i)); \n" +
163 " pp(pi) = yes; pi(p) = pi(p-1); \n" +
164 " else \n" +
165 " done = 1; \n" +
166 " ); \n" +
167 "); \n" +
168 "display 'lower bound for number of rolls', master.objval; \n" +
169 " \n" +
170 "option solprint=on; \n" +
171 "solve master using mip minimizing z; \n" +
172 " \n" +
173 "Parameter patrep Solution pattern report \n" +
174 " demrep Solution demand supply report; \n" +
175 " \n" +
176 "patrep('# produced',p) = round(xp.l(p)); \n" +
177 "patrep(i,p)$patrep('# produced',p) = aip(i,p); \n" +
178 "patrep(i,'total') = sum(p, patrep(i,p)); \n" +
179 "patrep('# produced','total') = sum(p, patrep('# produced',p)); \n" +
180 " \n" +
181 "demrep(i,'produced') = sum(p,patrep(i,p)*patrep('# produced',p)); \n" +
182 "demrep(i,'demand') = d(i); \n" +
183 "demrep(i,'over') = demrep(i,'produced') - demrep(i,'demand'); \n" +
184 " \n" +
185 "display patrep, demrep; \n" +
186 "$if not set dbOut1 $abort 'no file name for out-database 1 file provided' \n" +
187 "execute_unload '%dbOut1%', patrep; \n" +
188 " ";
189}
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::GAMSOptions::defines
void defines(String defStr, String asStr)
com::gams::api::GAMSOptions::getDefinitionOf
String getDefinitionOf(String str)
com::gams::api::GAMSOptions::setSolveLink
void setSolveLink(GAMSOptions.ESolveLink x)
com::gams::api::GAMSWorkspace::addDatabaseFromGDX
GAMSDatabase addDatabaseFromGDX(String gdxFileName)
com::gams::api::GAMSWorkspace::addJobFromString
GAMSJob addJobFromString(String source)
com::gams.examples.cutstock.CutstockModel
This example shows the wrapper model of a cutstock problem based on the simple GAMS [cutstock] model ...
Definition: CutstockModel.java:17
com::gams.examples.cutstock.CutstockModel.getWidths
GAMSSet getWidths()
get an input symbol, i : widths
Definition: CutstockModel.java:68
com::gams.examples.cutstock.CutstockModel.getDemand
GAMSParameter getDemand()
get an input symbol, d : demand
Definition: CutstockModel.java:74
com::gams.examples.cutstock.CutstockModel.run
void run()
Executes the cutstock model.
Definition: CutstockModel.java:51
com::gams.examples.cutstock.CutstockModel.getPatRep
GAMSParameter getPatRep()
get an output symbol, patrep : Solution pattern report
Definition: CutstockModel.java:80
com::gams.examples.cutstock.CutstockModel.getRawWidth
GAMSParameter getRawWidth()
get an input symbol, r : raw width
Definition: CutstockModel.java:71
com::gams.examples.cutstock.CutstockModel.getOpt
GAMSOptions getOpt()
get Options for the execution of the cutstock model
Definition: CutstockModel.java:83
com::gams.examples.cutstock.CutstockModel.getModelSource
String getModelSource()
get the source of cutstock model
Definition: CutstockModel.java:86
com::gams.examples.cutstock.CutstockModel.CutstockModel
CutstockModel(GAMSWorkspace ws)
CutstockModel constructor.
Definition: CutstockModel.java:32
com::gams.examples.cutstock.CutstockModel.run
void run(PrintStream output)
Executes the cutstock model.
Definition: CutstockModel.java:58
com::gams.examples.cutstock.CutstockModel.getWidth
GAMSParameter getWidth()
get an input symbol, w : width
Definition: CutstockModel.java:77
com::gams
Provides package namespace for Java interface and examples to General Algebraic Model System (GAMS).
com
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