package com.whyc.util;
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import com.whyc.pojo.TestParam;
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import java.math.BigDecimal;
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import java.math.RoundingMode;
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import java.util.Arrays;
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import java.util.List;
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import java.util.stream.Collectors;
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public class MathUtil {
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//均一性
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public static float getStandardDeviation(List<Float> list){
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//求平均值
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float avg = list.stream().collect(Collectors.averagingDouble(Float::floatValue)).floatValue();
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//求方差
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//相减,平方,累加
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float subSquareTotal = 0.0f;
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for (Float item : list) {
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subSquareTotal += (item -avg)*(item -avg);
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}
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Float s = subSquareTotal/list.size();
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//标准差
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double σ = Math.sqrt(s.doubleValue());
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return BigDecimal.valueOf(σ).setScale(4, RoundingMode.HALF_UP).floatValue();
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}
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//评判整组的好坏flag:1差，2良，3优 电压； 内阻越大越不好
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public static int getflag(float maxStd, float std, TestParam testParam){
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int flag=0;
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float judgeStdLow=0f;
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float judgeStdHigh=0f;
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maxStd=maxStd*100;
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if (testParam!=null){
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judgeStdLow=std*testParam.getResGoodCoeK3();
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judgeStdHigh=std*testParam.getResBadCoeK4();
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if(maxStd>=judgeStdHigh){
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flag=1;//"差"
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}else if(maxStd>=judgeStdLow){
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flag=2;//"良";
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}else{
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flag=3;//"优";
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}
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}
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return flag;
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}
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//评判整组的好坏flag:1 电压； 内阻越大越不好
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public static String getJudge(int flag){
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String judge="未知";
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switch (flag){
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case 1:judge="差";break;
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case 2:judge="良";break;
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case 3:judge="优";break;
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}
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return judge;
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}
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public static void main(String[] args) {
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Float[] f = {3.54f,3.55f,3.55f,3.56f,3.57f,3.56f,3.58f,3.58f,3.56f};
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Float[] f2 = {3.53f,3.55f,3.56f,3.57f,3.59f,3.58f,3.6f,3.6f,3.61f};
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Float standardDeviation = getStandardDeviation(Arrays.asList(f));
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Float standardDeviation2 = getStandardDeviation(Arrays.asList(f2));
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System.out.println(standardDeviation);
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System.out.println(standardDeviation2);
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}
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}
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