[32] | 1 | package geniusweb.ip.general;
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| 2 |
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| 3 | import java.util.Random;
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| 4 |
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| 5 | public class RandomSubsetOfGivenSet {
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| 6 | final private int[] givenSet;
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| 7 | final private int numOfElementsInGivenSet;
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| 8 | final private int sizeOfSubsetToBeSampled;
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| 9 | final private boolean subsetEqualsGivenSet;
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| 10 | private int[] availableIndicesToChooseFrom;
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| 11 | private Random randomGenerator;
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| 12 |
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| 13 | // ******************************************************************************************************
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| 14 |
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| 15 | /**
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| 16 | * The constructor:
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| 17 | *
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| 18 | * @param givenSet: The set from which subsets will be
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| 19 | * sampled
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| 20 | * @param numOfElementsInGivenSet: the number of elements in the set from
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| 21 | * which subsets will be sampled
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| 22 | * @param sizeOfSubsetToBeSampled: the size of every subset that will be
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| 23 | * sampled.
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| 24 | */
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| 25 | public RandomSubsetOfGivenSet(int[] givenSet, int numOfElementsInGivenSet,
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| 26 | int sizeOfSubsetToBeSampled) {
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| 27 | this.givenSet = givenSet;
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| 28 | this.numOfElementsInGivenSet = numOfElementsInGivenSet;
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| 29 | this.sizeOfSubsetToBeSampled = sizeOfSubsetToBeSampled;
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| 30 | this.randomGenerator = new Random();
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| 31 | this.availableIndicesToChooseFrom = new int[numOfElementsInGivenSet];
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| 32 | if (sizeOfSubsetToBeSampled == numOfElementsInGivenSet)
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| 33 | subsetEqualsGivenSet = true;
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| 34 | else
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| 35 | subsetEqualsGivenSet = false;
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| 36 | }
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| 37 |
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| 38 | // ******************************************************************************************************
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| 39 |
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| 40 | /**
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| 41 | * Returns random subset of size: "sizeOfSubsetToBeSampled", taken from the
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| 42 | * set: "givenSet"
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| 43 | */
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| 44 | public int[] getSubsetInByteFormat() {
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| 45 | if (this.subsetEqualsGivenSet) {
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| 46 | int[] copyOfGivenSet = new int[numOfElementsInGivenSet];
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| 47 | for (int i = 0; i < numOfElementsInGivenSet; i++) {
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| 48 | copyOfGivenSet[i] = givenSet[i];
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| 49 | }
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| 50 | return copyOfGivenSet;
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| 51 | } else {
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| 52 | // this.randomGenerator = new Random();
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| 53 | for (int i = numOfElementsInGivenSet - 1; i >= 0; i--) {
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| 54 | availableIndicesToChooseFrom[i] = i;
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| 55 | }
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| 56 | int[] subsetInByteFormat = new int[sizeOfSubsetToBeSampled];
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| 57 | int indexInSubset = 0;
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| 58 | for (int i = numOfElementsInGivenSet
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| 59 | - 1; i >= numOfElementsInGivenSet
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| 60 | - sizeOfSubsetToBeSampled; i--) {
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| 61 | int j = this.randomGenerator.nextInt(i + 1);
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| 62 | subsetInByteFormat[indexInSubset] = givenSet[availableIndicesToChooseFrom[j]];
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| 63 | indexInSubset++;
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| 64 | availableIndicesToChooseFrom[j] = availableIndicesToChooseFrom[i];
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| 65 | }
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| 66 | return subsetInByteFormat;
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| 67 | }
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| 68 | }
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| 69 |
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| 70 | // ******************************************************************************************************
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| 71 |
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| 72 | /**
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| 73 | * Returns random subset of size: "sizeOfSubsetToBeSampled", taken from the
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| 74 | * set: "givenSet"
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| 75 | */
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| 76 | public int getSubsetInBitFormat() {
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| 77 | if (this.subsetEqualsGivenSet) {
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| 78 | int copyOfGivenSet = 0;
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| 79 | for (int i = 0; i < numOfElementsInGivenSet; i++) {
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| 80 | // Add agent "givenSet[i]" to "copyOfGivenSet"
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| 81 | copyOfGivenSet += 1 << (givenSet[i] - 1);
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| 82 | }
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| 83 | return copyOfGivenSet;
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| 84 | } else {
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| 85 | // this.randomGenerator = new Random();
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| 86 | for (int i = numOfElementsInGivenSet - 1; i >= 0; i--) {
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| 87 | availableIndicesToChooseFrom[i] = i;
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| 88 | }
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| 89 | int subsetInBitFormat = 0;
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| 90 | int indexInSubset = 0;
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| 91 | for (int i = numOfElementsInGivenSet
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| 92 | - 1; i >= numOfElementsInGivenSet
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| 93 | - sizeOfSubsetToBeSampled; i--) {
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| 94 | int j = this.randomGenerator.nextInt(i + 1);
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| 95 | // Add agent "givenSet[ availableIndicesToChooseFrom[ j ] ]" to
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| 96 | // "subsetInBitFormat"
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| 97 | subsetInBitFormat += 1 << (givenSet[availableIndicesToChooseFrom[j]]
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| 98 | - 1);
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| 99 | indexInSubset++;
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| 100 | availableIndicesToChooseFrom[j] = availableIndicesToChooseFrom[i];
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| 101 | }
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| 102 | return subsetInBitFormat;
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| 103 | }
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| 104 | }
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| 105 | }
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