package com.whyc.service;
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import java.text.DecimalFormat;
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import java.util.Arrays;
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import java.util.List;
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public class TestLineXY {
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public static void main(String[] args) {
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DecimalFormat df = new DecimalFormat("0.##");
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//x pv
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//y uv
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List<Integer> x = Arrays.asList(5, 9, 15, 19, 19, 45);
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List<Integer> y = Arrays.asList(4, 6, 12, 15, 15, 37);
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/*
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List x=Arrays.asList(4,6,8,10,12);
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List y=Arrays.asList(7.8d,9.3d,9.9d,11.2d,11.9d);
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*/
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System.out.println(x + "" + y);
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if (x.size() != y.size()) {
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System.out.println("分子分母数量不一致。");
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return;
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}
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long sum = 0;
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for (Integer xi : x) {
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sum += xi;
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}
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double avgx = sum * 1.0 / y.size();
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System.out.println("avg_x:" + avgx);
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//w的分子
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double w_molecule = 0;
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for (int i = 0; i < x.size(); i++) {
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w_molecule += y.get(i) * (x.get(i) - avgx);
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}
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//w的分母
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double w_denominator = 0;
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int w_denominator_xi = 0;
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for (int i = 0; i < x.size(); i++) {
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w_denominator += Math.pow(x.get(i), 2);
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w_denominator_xi += x.get(i);
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}
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w_denominator = w_denominator - (1.0 / x.size()) * (Math.pow(w_denominator_xi, 2));
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//System.out.println("w_denominator:"+w_denominator+" w_denominator_xi:"+w_denominator_xi);
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double w = w_molecule / w_denominator;
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System.out.println("w:" + w);
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double b = 1.0 / x.size();
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double sum_y_wx = 0;
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for (int i = 0; i < x.size(); i++) {
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sum_y_wx += (y.get(i) - w * x.get(i));
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}
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b = b * sum_y_wx;
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System.out.println("b:" + b);
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String symbol = "+";
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if (b < 0) {
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symbol = "";
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}
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System.out.println("y=" + df.format(w) + "x" + symbol + df.format(b));
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System.out.println(w * 15 + b);
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}
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}
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