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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchlib.ranking.features.fieldmatch;
import org.junit.Before;
import org.junit.Test;
import java.util.Set;
import java.util.HashSet;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
/**
* The "semantic distance" refers to the non-continuous distance from a token
* to the next token used by the string match metrics algorithm. This class
* tests invariants which must hold for any such distance metric as well as specifics
* for the currently used distance metric.
*
* @author bratseth
*/
public class SemanticDistanceTestCase {
FieldMatchMetricsComputer c;
@Before
public void setUp() {
c=new FieldMatchMetricsComputer();
StringBuilder field = new StringBuilder();
for (int i = 0; i < 150; i++)
field.append("t" + i + " ");
c.compute("query", field.toString()); // Just to set the field value
}
/** Must be true using any semantic distance function */
@Test
public void testBothWayConversionProducesOriginalValue() {
assertBothWayConversionProducesOriginalValue(50);
assertBothWayConversionProducesOriginalValue(10);
assertBothWayConversionProducesOriginalValue(5);
assertBothWayConversionProducesOriginalValue(0);
assertBothWayConversionProducesOriginalValue(140);
assertBothWayConversionProducesOriginalValue(145);
assertBothWayConversionProducesOriginalValue(149);
}
/** Must be true using any semantic distance function */
@Test
public void testFunctionsAreOneToOne() {
assertFunctionsAreOneToOne(50);
assertFunctionsAreOneToOne(10);
assertFunctionsAreOneToOne(5);
assertFunctionsAreOneToOne(0);
assertFunctionsAreOneToOne(140);
assertFunctionsAreOneToOne(145);
assertFunctionsAreOneToOne(149);
}
/** Specific to this particular distance function */
@Test
public void testFunction() {
int zeroJ = 50;
assertFunction(50,0, zeroJ);
assertFunction(59,9, zeroJ);
assertFunction(49,10, zeroJ);
assertFunction(40,19, zeroJ);
assertFunction(60,20, zeroJ);
assertFunction(149,109, zeroJ);
assertFunction(39,110, zeroJ);
assertFunction(0,149, zeroJ);
zeroJ = 0;
assertFunction(0,0, zeroJ);
assertFunction(10,10, zeroJ);
assertFunction(20,20, zeroJ);
assertFunction(149,149, zeroJ);
zeroJ = 5;
assertFunction(5,0, zeroJ);
assertFunction(10,5, zeroJ);
assertFunction(14,9, zeroJ);
assertFunction(4,10, zeroJ);
assertFunction(0,14, zeroJ);
assertFunction(15,15, zeroJ);
assertFunction(25,25, zeroJ);
assertFunction(149,149, zeroJ);
zeroJ = 149;
assertFunction(149,0, zeroJ);
assertFunction(140,9, zeroJ);
assertFunction(130,19, zeroJ);
assertFunction(0,149, zeroJ);
zeroJ = 145;
assertFunction(145,0, zeroJ);
assertFunction(149,4, zeroJ);
assertFunction(144,5, zeroJ);
assertFunction(140,9, zeroJ);
assertFunction(135,14, zeroJ);
assertFunction(125,24, zeroJ);
assertFunction(0,149, zeroJ);
}
/** Hits both limits at once */
@Test
public void testSmallField() {
c = new FieldMatchMetricsComputer();
c.compute("query","my field value four"); // Just to set the field value
assertBothWayConversionProducesOriginalValue(2);
assertBothWayConversionProducesOriginalValue(0);
assertBothWayConversionProducesOriginalValue(3);
assertFunctionsAreOneToOne(2);
assertFunctionsAreOneToOne(0);
assertFunctionsAreOneToOne(3);
int zeroJ=2;
assertFunction(2,0, zeroJ);
assertFunction(3,1, zeroJ);
assertFunction(1,2, zeroJ);
assertFunction(0,3, zeroJ);
}
private void assertBothWayConversionProducesOriginalValue(int zeroJ) {
// Starting point in the middle
for (int j = 0; j < c.getField().terms().size(); j++) {
int semanticDistance=c.fieldIndexToSemanticDistance(j, zeroJ);
assertTrue("Using zeroJ=" + zeroJ + ": " + semanticDistance +">=0", semanticDistance >= 0);
int backConvertedJ=c.semanticDistanceToFieldIndex(semanticDistance, zeroJ);
assertEquals("Using zeroJ=" + zeroJ + ": " + j + "->" + semanticDistance + "->" + backConvertedJ,j, backConvertedJ);
}
}
private void assertFunctionsAreOneToOne(int zeroJ) {
Set<Integer> distances = new HashSet<>();
for (int j = 0; j < c.getField().terms().size(); j++) {
int semanticDistance = c.fieldIndexToSemanticDistance(j,zeroJ);
assertTrue("Using zeroJ=" + zeroJ + ": " + j + "->" + semanticDistance + " is unique",
! distances.contains(semanticDistance));
distances.add(semanticDistance);
}
}
private void assertFunction(int j,int semanticDistance, int zeroJ) {
assertEquals(j + "->" + semanticDistance,semanticDistance, c.fieldIndexToSemanticDistance(j,zeroJ));
}
}
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