Page 173 - 49A Field Guide to Genetic Programming

B.3 Source Code 159

202 ind = new char [ len ] ;
203
204 System . arraycopy ( buffer , 0 , ind , 0 , len ) ;
205 return ( ind ) ;
206 }
207
208 char [ ] [ ] create random pop ( int n , int depth , double [ ]
f i t n e s s ) {
209 char [ ] [ ] pop = new char [ n ] [ ] ;
210 int i ;
211
212 for ( i = 0; i < n ; i ++ ) {
213 pop [ i ] = create random indiv ( depth ) ;
214 f i t n e s s [ i ] = f i t n e s s f u n c t i o n ( pop [ i ] ) ;
215 }
216 return ( pop ) ;
217 }
218
219
220 void s t a t s ( double [ ] f i t n e s s , char [ ] [ ] pop , int gen ) {
221 int i , best = rd . nextInt (POPSIZE) ;
222 int node count = 0 ;
223 fbestpop = f i t n e s s [ best ] ;
224 favgpop = 0 . 0 ;
225
226 for ( i = 0; i < POPSIZE ; i ++ ) {
227 node count += t r a v e r s e ( pop [ i ] , 0 ) ;
228 favgpop += f i t n e s s [ i ] ;
229 i f ( f i t n e s s [ i ] > fbestpop ) {
230 best = i ;
231 fbestpop = f i t n e s s [ i ] ;
232 }
233 }
234 avg len = ( double ) node count / POPSIZE ;
235 favgpop /= POPSIZE ;
236 System . out . print ( ” Generation=”+gen+” Avg Fitness=”+(−favgpop
)+
237 ” Best Fitness=”+(−fbestpop )+” Avg Size=”+
avg len+
238 ”\nBest In d i v i d u a l : ” ) ;
239 p r i n t i n d i v ( pop [ best ] , 0 ) ;
240 System . out . print ( ”\n” ) ;
241 System . out . f l u s h ( ) ;
242 }
243
244 int tournament ( double [ ] f i t n e s s , int t s i z e ) {
245 int best = rd . nextInt (POPSIZE) , i , competitor ;
246 double f b e s t = −1.0 e34 ;
247
248 for ( i = 0; i < t s i z e ; i ++ ) {
249 competitor = rd . nextInt (POPSIZE) ;
250 i f ( f i t n e s s [ competitor ] > f b e s t ) {
251 f b e s t = f i t n e s s [ competitor ] ;
252 best = competitor ;
253 }