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fc623db0ca
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@t2652009480
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fc623db0ca | 7 months ago |
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@t2652009480
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48588b59aa | 7 months ago |
@ -1,121 +1,44 @@
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package com.sztzjy.marketing.util.algorithm;
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import com.sztzjy.marketing.util.BigDecimalUtils;
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import java.text.DecimalFormat;
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public class LogisticRegression {
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private double theta0; // 截距项
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private double theta1; // 斜率
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private double learningRate; // 学习率
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private int currentEpoch; // 声明currentEpoch变量
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public LogisticRegression(double learningRate) {
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this.learningRate = learningRate;
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}
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private double[] x;
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private double[] y;
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public LogisticRegression(double learningRate, double initialTheta0, double initialTheta1) {
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this.learningRate = learningRate;
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this.theta0 = initialTheta0;
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this.theta1 = initialTheta1;
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this.currentEpoch = 0; // 在构造函数中初始化currentEpoch
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public LogisticRegression(double[] x, double[] y) {
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this.x = x;
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this.y = y;
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}
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// 添加一个方法来获取截距项
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public double getIntercept() {
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return theta0;
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// 计算线性回归参数
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public double[] fit() {
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if (x.length != y.length || x.length == 0) {
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throw new IllegalArgumentException("Invalid input data");
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}
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// 添加一个方法来获取第一个特征的系数
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public double getCoefficient() {
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return theta1;
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}
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int n = x.length;
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double sumX = 0;
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double sumY = 0;
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double sumXY = 0;
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double sumXX = 0;
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// Sigmoid函数
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private double sigmoid(double z) {
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return 1 / (1 + Math.exp(-z));
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// 计算各项和
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for (int i = 0; i < n; i++) {
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sumX += x[i];
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sumY += y[i];
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sumXY += x[i] * y[i];
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sumXX += x[i] * x[i];
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}
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// 预测函数
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public double predict(double x,double slopes,double intercept) {
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BigDecimalUtils bigDecimalUtils=new BigDecimalUtils();
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Double mul = bigDecimalUtils.mul(intercept, x);
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return bigDecimalUtils.add(slopes, mul);
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// 计算斜率和截距
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double slope = (n * sumXY - sumX * sumY) / (n * sumXX - sumX * sumX);
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double intercept = (sumY - slope * sumX) / n;
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return new double[] { intercept, slope };
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}
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private double dotProduct(double[] a, double[] b) {
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double result = 0.0;
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for (int i = 0; i < a.length; i++) {
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result += a[i] * b[i];
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}
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return result;
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}
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//
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// // 梯度下降更新参数
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// public void updateParameters(double x, double y) {
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// double h = predict(x);
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// double error = y - h;
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// theta1 += learningRate * error * h * (1 - h) * x;
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// theta0 += learningRate * error * h * (1 - h);
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// }
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private double exponentialDecayLearningRate(double currentEpoch, int totalEpochs) {
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return learningRate * Math.exp(-(currentEpoch / totalEpochs));
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}
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// 训练模型
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public void train(double[][] data, double[] labels, int epochs) {
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double learningRateCurrentEpoch = exponentialDecayLearningRate(currentEpoch, epochs);
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for (int epoch = 0; epoch < epochs; epoch++) {
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for (int i = 0; i < data.length; i++) {
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double x = data[i][0];
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double y = labels[i];
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double h = sigmoid(theta0 + theta1 * x);
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double error = y - h;
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theta1 += learningRateCurrentEpoch * error * h * (1 - h) * x;
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theta0 += learningRateCurrentEpoch * error * h * (1 - h);
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}
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// 可以添加打印语句查看训练情况
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// System.out.println("Epoch: " + (epoch + 1) + ", Loss: " + calculateLoss(data, labels));
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}
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}
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public double calculateLoss(double[][] data, double[] labels) {
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double loss = 0;
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for (int i = 0; i < data.length; i++) {
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double x = data[i][0];
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double y = labels[i];
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double h = sigmoid(theta0 + theta1 * x);
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loss += -y * Math.log(h) - (1 - y) * Math.log(1 - h);
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}
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return loss / data.length;
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}
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// public static void main(String[] args) {
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// LogisticRegression model = new LogisticRegression(0.1); // 创建一个逻辑回归模型实例
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//
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//// double[][] data = {{1}, {2}, {3}, {4}, {5}};
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//// double[] labels = {0, 0, 1, 1, 1}; // 假设这是一个二分类问题
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//
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// double[][] data = {{1, 19}, {1, 21}, {2, 20}, {2, 23}, {2, 31}};
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// double[] labels = {15, 15, 16, 16, 17};
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//
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// model.train(data, labels, 1000); // 训练模型
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//
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// DecimalFormat df = new DecimalFormat("#.0");
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//
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// // 获取并打印截距项和系数
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// double intercept = model.getIntercept();
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// double coefficient = model.getCoefficient();
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// System.out.println("常数项值: " + df.format(intercept));
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// System.out.println("系数值 " + df.format(coefficient));
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//
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// double prediction = model.predict(2);
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// System.out.println("x=3.5的预测： " + df.format(prediction));
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// }
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}
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