org.elasticsearch.common.util.ArrayUtils Maven / Gradle / Ivy
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* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.common.util;
import java.util.Arrays;
/**
*
*/
public class ArrayUtils {
private ArrayUtils() {}
/**
* Return the index of value in array, or -1 if there is no such index.
* If there are several values that are within tolerance or less of value, this method will return the
* index of the closest value. In case of several values being as close ot value, there is no guarantee which index
* will be returned.
* Results are undefined if the array is not sorted.
*/
public static int binarySearch(double[] array, double value, double tolerance) {
if (array.length == 0) {
return -1;
}
return binarySearch(array, 0, array.length, value, tolerance);
}
private static int binarySearch(double[] array, int fromIndex, int toIndex, double value, double tolerance) {
int index = Arrays.binarySearch(array, fromIndex, toIndex, value);
if (index < 0) {
final int highIndex = -1 - index; // first index of a value that is > value
final int lowIndex = highIndex - 1; // last index of a value that is < value
double lowError = Double.POSITIVE_INFINITY;
double highError = Double.POSITIVE_INFINITY;
if (lowIndex >= 0) {
lowError = value - array[lowIndex];
}
if (highIndex < array.length) {
highError = array[highIndex] - value;
}
if (highError < lowError) {
if (highError < tolerance) {
index = highIndex;
}
} else if (lowError < tolerance) {
index = lowIndex;
} else {
index = -1;
}
}
return index;
}
}