package com.tievd.jyz.util;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* 百分比工具类
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*
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* @author yang'zhi'shui
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*/
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public class PercentUtil {
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/**
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* 百分之和校准等于1
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*
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* @param arr 集合
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* @param sum 总数
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* @param precision 精度
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* @return
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*/
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public static List<Double> getPercentValue(List<Double> arr, double sum, int precision) {
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Double[] seats = new Double[arr.size()];
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//10的2次幂是100，用于计算精度。
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double digits = Math.pow(10, precision);
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for (int idx = 0; idx < arr.size(); idx++) {
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//求和
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if (sum <= 0) {
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for (int i = 0; i < arr.size(); i++) {
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sum += arr.get(i);
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}
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}
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//扩大比例100
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double[] votesPerQuota = new double[arr.size()];
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for (int i = 0; i < arr.size(); i++) {
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double val = arr.get(i) / sum * digits * 100;
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votesPerQuota[i] = val;
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}
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//总数,扩大比例意味的总数要扩大
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double targetSeats = digits * 100;
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//再向下取值，组成数组
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for (int i = 0; i < votesPerQuota.length; i++) {
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seats[i] = Math.floor(votesPerQuota[i]);
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}
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//再新计算合计，用于判断与总数量是否相同,相同则占比会100%
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double currentSum = 0;
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for (int i = 0; i < seats.length; i++) {
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currentSum += seats[i];
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}
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//余数部分的数组:原先数组减去向下取值的数组,得到余数部分的数组
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double[] remainder = new double[arr.size()];
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for (int i = 0; i < seats.length; i++) {
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remainder[i] = votesPerQuota[i] - seats[i];
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}
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while (currentSum < targetSeats) {
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double max = 0;
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int maxId = 0;
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int len = 0;
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for (int i = 0; i < remainder.length; ++i) {
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if (remainder[i] > max) {
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max = remainder[i];
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maxId = i;
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}
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}
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//对最大项余额加1
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++seats[maxId];
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//已经增加最大余数加1,则下次判断就可以不需要再判断这个余额数。
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remainder[maxId] = 0;
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//总的也要加1,为了判断是否总数是否相同,跳出循环。
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++currentSum;
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}
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}
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List<Double> list = new ArrayList<>();
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for (int i = 0; i < seats.length; i++) {
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list.add(i, seats[i] / digits / 100);
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}
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return list;
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}
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}
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