47 lines
1.7 KiB
Java
47 lines
1.7 KiB
Java
package com.baeldung.lsh;
|
|
|
|
import info.debatty.java.lsh.LSHMinHash;
|
|
import org.junit.Ignore;
|
|
import org.junit.Test;
|
|
|
|
import java.util.Arrays;
|
|
|
|
import static org.assertj.core.api.Assertions.assertThat;
|
|
|
|
public class LocalSensitiveHashingUnitTest {
|
|
|
|
@Ignore("for simplicity of the example number of input vectors is very low, that's why LSH may yield non deterministic results")
|
|
@Test()
|
|
public void givenNVectors_whenPerformLSH_thenShouldCalculateSameHashForSimilarVectors() {
|
|
// given
|
|
boolean[] vector1 = new boolean[] { true, true, true, true, true };
|
|
boolean[] vector2 = new boolean[] { false, false, false, true, false };
|
|
boolean[] vector3 = new boolean[] { false, false, true, true, false };
|
|
|
|
int sizeOfVectors = 5;
|
|
int numberOfBuckets = 10;
|
|
int stages = 4;
|
|
|
|
LSHMinHash lsh = new LSHMinHash(stages, numberOfBuckets, sizeOfVectors);
|
|
|
|
// when
|
|
int[] firstHash = lsh.hash(vector1);
|
|
int[] secondHash = lsh.hash(vector2);
|
|
int[] thirdHash = lsh.hash(vector3);
|
|
|
|
System.out.println(Arrays.toString(firstHash));
|
|
System.out.println(Arrays.toString(secondHash));
|
|
System.out.println(Arrays.toString(thirdHash));
|
|
|
|
// then
|
|
int lastIndexOfResult = stages - 1;
|
|
assertThat(firstHash[lastIndexOfResult]).isNotEqualTo(secondHash[lastIndexOfResult]);
|
|
assertThat(firstHash[lastIndexOfResult]).isNotEqualTo(thirdHash[lastIndexOfResult]);
|
|
assertThat(isCloseOrEqual(secondHash[lastIndexOfResult], thirdHash[lastIndexOfResult], numberOfBuckets)).isTrue();
|
|
}
|
|
|
|
private boolean isCloseOrEqual(int secondHash, int thirdHash, int numberOfBuckets) {
|
|
return Math.abs(secondHash - thirdHash) < numberOfBuckets / 2;
|
|
}
|
|
}
|