[6152] | 1 | /* |
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| 2 | Copyright 2006 by Sean Luke and George Mason University |
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| 3 | Licensed under the Academic Free License version 3.0 |
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| 4 | See the file "LICENSE" for more information |
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| 5 | */ |
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| 6 | |
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| 7 | package ec.spatial; |
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| 8 | |
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| 9 | import ec.*; |
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| 10 | import ec.util.*; |
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| 11 | |
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| 12 | /* |
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| 13 | * Spatial1DSubpopulation.java |
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| 14 | * |
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| 15 | * By: Liviu Panait |
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| 16 | */ |
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| 17 | |
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| 18 | /** |
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| 19 | * A Spatial1DSubpopulation is an EC subpopulation that is additionally embedded into |
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| 20 | * a one-dimmensional space. |
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| 21 | * In a spatially-embedded EA, the subpopulations of individuals are assumed to be |
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| 22 | * spatially distributed in some sort of space, be it one-dimmensional, two- |
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| 23 | * dimmensional, or whatever else. The space may or may not be toroidal (although |
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| 24 | * it usually is). Each location in the space has a set of neighboring locations. |
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| 25 | * Thus, each individual has an index in the subpopulation, and also a location in |
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| 26 | * the space. |
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| 27 | * |
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| 28 | * <p>This public interface provides a method to obtain the indexes of the neighbors |
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| 29 | * of a location. |
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| 30 | * |
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| 31 | * <P>This Subpopulation does not include toroidalness in writing out to streams. |
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| 32 | * |
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| 33 | <p><b>Parameters</b><br> |
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| 34 | <table> |
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| 35 | <tr><td valign=top><tt>toroidal</tt><br> |
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| 36 | <font size=-1>true (default) or false</font></td> |
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| 37 | <td valign=top>(Is this space toroidal?)</td></tr> |
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| 38 | |
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| 39 | * |
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| 40 | * |
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| 41 | * @author Liviu Panait |
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| 42 | * @version 1.0 |
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| 43 | */ |
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| 44 | public class Spatial1DSubpopulation extends Subpopulation implements Space |
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| 45 | { |
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| 46 | /** |
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| 47 | This parameter stipulates whether the world is toroidal or not. |
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| 48 | If missing, its default value is true. |
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| 49 | */ |
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| 50 | public static final String P_TOROIDAL = "toroidal"; |
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| 51 | public boolean toroidal; |
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| 52 | |
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| 53 | /** |
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| 54 | Read additional parameters for the spatially-embedded subpopulation. |
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| 55 | */ |
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| 56 | public void setup(final EvolutionState state, final Parameter base) |
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| 57 | { |
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| 58 | super.setup(state,base); |
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| 59 | |
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| 60 | // by default, the space is toroidal |
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| 61 | toroidal = state.parameters.getBoolean(base.push(P_TOROIDAL),null,true); |
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| 62 | |
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| 63 | } |
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| 64 | |
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| 65 | /* |
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| 66 | 1D mapping is identity |
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| 67 | */ |
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| 68 | /* |
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| 69 | public int locationToIndex( final Object location ) |
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| 70 | { |
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| 71 | if( location instanceof Integer ) |
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| 72 | return ((Integer)location).intValue(); |
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| 73 | return -1; |
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| 74 | } |
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| 75 | */ |
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| 76 | |
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| 77 | /* |
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| 78 | 1D mapping is identity |
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| 79 | */ |
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| 80 | /* |
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| 81 | public Object indexToLocation( final int index) |
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| 82 | { |
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| 83 | return new Integer(index); |
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| 84 | } |
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| 85 | */ |
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| 86 | |
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| 87 | public void setIndex( int threadnum, int index ) |
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| 88 | { |
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| 89 | if( indexes == null ) |
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| 90 | indexes = new int[threadnum+1]; |
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| 91 | if( threadnum >= indexes.length ) |
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| 92 | { |
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| 93 | int currentSize = indexes.length; |
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| 94 | int[] temp = new int[threadnum*2+1]; |
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| 95 | System.arraycopy(indexes,0,temp,0,currentSize); |
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| 96 | indexes = temp; |
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| 97 | } |
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| 98 | indexes[threadnum] = index; |
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| 99 | } |
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| 100 | |
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| 101 | public int getIndex( int threadnum ) |
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| 102 | { |
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| 103 | if( indexes == null || threadnum > indexes.length ) |
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| 104 | return -1; |
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| 105 | else |
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| 106 | return indexes[threadnum]; |
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| 107 | } |
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| 108 | |
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| 109 | // indexed by threadnum |
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| 110 | int[] indexes; |
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| 111 | |
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| 112 | /** |
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| 113 | Returns a the index of a random neighbor. |
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| 114 | */ |
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| 115 | public int getIndexRandomNeighbor( final EvolutionState state, int threadnum, int distance ) |
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| 116 | { |
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| 117 | int index = indexes[threadnum]; |
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| 118 | |
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| 119 | int size = individuals.length; |
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| 120 | if( size == 0 ) |
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| 121 | return index; |
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| 122 | if( toroidal ) |
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| 123 | { |
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| 124 | int max = (2*distance+1>size) ? size : (2*distance+1); |
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| 125 | int rand = state.random[threadnum].nextInt(max); |
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| 126 | int val= (index+rand-distance); |
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| 127 | if (val >= 0 && val < size) return val; |
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| 128 | val = val % size; |
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| 129 | if (val >= 0) return val; |
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| 130 | else return val + size; |
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| 131 | } |
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| 132 | else |
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| 133 | { |
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| 134 | int min = (index-distance<0) ? 0 : (index-distance); |
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| 135 | int max = (index+distance>=size) ? size : (index+distance); |
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| 136 | int val = min + state.random[threadnum].nextInt(max-min+1); |
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| 137 | return val; |
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| 138 | } |
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| 139 | } |
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| 140 | } |
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