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weihongyang
160
ym-common/src/main/java/com/cnbm/common/utils/CountUtils.java
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160
ym-common/src/main/java/com/cnbm/common/utils/CountUtils.java
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package com.cnbm.common.utils;
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import java.math.BigDecimal;
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import java.math.BigInteger;
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import java.util.ArrayList;
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import java.util.List;
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import static java.math.BigDecimal.ROUND_HALF_UP;
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public class CountUtils {
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// private static final BigDecimal TWO = BigDecimal.valueOf(2);
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//
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// public static BigDecimal Mean(List<BigDecimal> data){
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// BigDecimal sum = new BigDecimal("0");
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// for (BigDecimal datum : data) {
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// sum = sum.add(datum);
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// }
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// BigDecimal divide = sum.divide(BigDecimal.valueOf(data.size()));
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// return divide;
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// }
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//
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// // population variance 总体方差
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// public static BigDecimal POP_Variance(List<BigDecimal> data) {
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// BigDecimal variance = new BigDecimal("0");
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// for (BigDecimal datum : data) {
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// variance = variance.add(datum.subtract(Mean(data)).pow(2));
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// }
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// variance = variance.divide(BigDecimal.valueOf(data.size()));
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// return variance;
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// }
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//
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// // population standard deviation 总体标准差
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// public static BigDecimal POP_STD_dev(List<BigDecimal> data) {
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// BigDecimal sqrt = sqrt(POP_Variance(data), 4);
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// return sqrt;
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// }
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//
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// //sample variance 样本方差
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// public static BigDecimal Sample_Variance(List<BigDecimal> data) {
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// BigDecimal variance = new BigDecimal("0");
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// for (BigDecimal datum : data) {
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// variance = variance.add(datum.subtract(Mean(data)).pow(2));
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// }
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// variance = variance.divide(BigDecimal.valueOf(data.size() - 1),4);
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// return variance;
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// }
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//
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// // sample standard deviation 样本标准差
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// public static BigDecimal Sample_STD_dev(List<BigDecimal> data) {
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// BigDecimal sqrt = sqrt(Sample_Variance(data), 4);
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// return sqrt;
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// }
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//
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// public static BigDecimal sqrt(BigDecimal A, final int SCALE) {
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// BigDecimal x0 = new BigDecimal("0");
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// BigDecimal x1 = new BigDecimal(Math.sqrt(A.doubleValue()));
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// while (!x0.equals(x1)) {
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// x0 = x1;
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// x1 = A.divide(x0, SCALE, ROUND_HALF_UP);
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// x1 = x1.add(x0);
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// x1 = x1.divide(TWO, SCALE, ROUND_HALF_UP);
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//
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// }
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// return x1;
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// }
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double Sum(double[] data) {
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double sum = 0;
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for (int i = 0; i < data.length; i++)
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sum = sum + data[i];
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return sum;
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}
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double Mean(double[] data) {
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double mean = 0;
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mean = Sum(data) / data.length;
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return mean;
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}
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// population variance 总体方差
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double POP_Variance(double[] data) {
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double variance = 0;
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for (int i = 0; i < data.length; i++) {
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variance = variance + (Math.pow((data[i] - Mean(data)), 2));
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}
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variance = variance / data.length;
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return variance;
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}
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// population standard deviation 总体标准差
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double POP_STD_dev(double[] data) {
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double std_dev;
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std_dev = Math.sqrt(POP_Variance(data));
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return std_dev;
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}
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//sample variance 样本方差
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double Sample_Variance(double[] data) {
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double variance = 0;
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for (int i = 0; i < data.length; i++) {
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variance = variance + (Math.pow((data[i] - Mean(data)), 2));
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}
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variance = variance / (data.length-1);
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return variance;
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}
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// sample standard deviation 样本标准差
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double Sample_STD_dev(double[] data) {
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double std_dev;
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std_dev = Math.sqrt(Sample_Variance(data));
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return std_dev;
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}
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public static void main(String[] args) {
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// List<BigDecimal> data = new ArrayList<>();
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//
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// data.add(new BigDecimal("10.023"));
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// data.add(new BigDecimal("11.02"));
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// data.add(new BigDecimal("9.99"));
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// data.add(new BigDecimal("9.81"));
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// data.add(new BigDecimal("10.12"));
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// data.add(new BigDecimal("10.9"));
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// data.add(new BigDecimal("9.99"));
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// data.add(new BigDecimal("10.03"));
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// data.add(new BigDecimal("9.99"));
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// data.add(new BigDecimal("12.02"));
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// CountUtils countUtils = new CountUtils();
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//
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// BigDecimal mean = countUtils.Mean(data);
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// System.out.println(mean.toString());
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//
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//
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// BigDecimal bigDecimal1 = POP_STD_dev(data);
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// System.out.println(bigDecimal1.toString());
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//
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// System.out.println(Sample_STD_dev(data).toString());
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//
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// BigDecimal bigDecimal = POP_Variance(data);
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// System.out.println(bigDecimal.toString());
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//
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//
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// System.out.println(Sample_Variance(data));
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double[] data = new double[]{10.023,11.02,9.99,9.81,10.12,10.9,9.99,10.03,9.99,12.02};
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CountUtils countUtils = new CountUtils();
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System.out.println(countUtils.Mean(data));
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System.out.println(countUtils.POP_STD_dev(data));
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System.out.println(countUtils.Sample_STD_dev(data));
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System.out.println(countUtils.POP_Variance(data));
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System.out.println(countUtils.Sample_Variance(data));
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}
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}
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@@ -0,0 +1,90 @@
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package com.cnbm.common.utils;
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public class LeastSquares
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{
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/*
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* 杜航 功能：返回估计的y值
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*/
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public static float estimate(float[] x, float[] y, float input)
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{
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float a = getA(x, y);
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float b = getB(x, y);
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System.out.println("线性回归系数a值：\t" + a + "\n" + "线性回归系数b值：\t" + b);
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return (a * input + b);
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}
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/*
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* 杜航 功能：返回x的系数a 公式：a = ( n sum( xy ) - sum( x ) sum( y ) ) / ( n sum( x^2 )
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* - sum(x) ^ 2 )
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*/
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public static float getA(float[] x, float[] y)
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{
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int n = x.length;
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return (float) ((n * pSum(x, y) - sum(x) * sum(y)) / (n * sqSum(x) - Math
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.pow(sum(x), 2)));
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}
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/*
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* 杜航 功能：返回常量系数系数b 公式：b = sum( y ) / n - a sum( x ) / n
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*/
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public static float getB(float[] x, float[] y)
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{
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int n = x.length;
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float a = getA(x, y);
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return sum(y) / n - a * sum(x) / n;
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}
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/*
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* 杜航 功能：求和
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*/
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private static float sum(float[] ds)
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{
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float s = 0;
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for (float d : ds)
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{
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s = s + d;
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}
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return s;
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}
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/*
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* 杜航 功能：求平方和
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*/
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private static float sqSum(float[] ds)
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{
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float s = 0;
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for (float d : ds)
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{
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s = (float) (s + Math.pow(d, 2));
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}
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return s;
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}
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/*
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* 杜航 功能：返回对应项相乘后的和
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*/
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private static float pSum(float[] x, float[] y)
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{
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float s = 0;
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for (int i = 0; i < x.length; i++)
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{
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s = s + x[i] * y[i];
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}
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return s;
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}
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/*
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* 杜航 功能：main()测试线性回归的最小二乘法java实现函数
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*/
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public static void main(String[] args)
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{
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float[] x =
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// { 540, 360, 240, 480, 420 };
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{ 0.501F, 0.482F, 0.482F, 0.51F, 0.492F, 0.54F, 0.5F, 0.492F, 0.51F, 0.489F};
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float[] y =
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// { 520, 475, 430, 386, 500 };
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{10.023F, 11.02F, 9.99F, 9.81F, 10.12F,10.9F, 9.99F, 10.03F, 9.99F, 12.02F };
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System.out.println("经线性回归后的y值：\t" + estimate(x, y,240));
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}
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}
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