@[toc]
前言
本文以求解二元函数最小值为例，如果需要求解多元函数，只需要修改以下变量即可：
varNum：变量维度数
ub和lb：变量的上下界
vMaxArr：每个维度的搜索速度限制
优化目标
目标：在变量区间范围最小化 Z = x^2 + y^2 - xy - 10x - 4y +60
求解结果
变量取值为：[7.9999860637249585, 5.999987161740172]
最优解为：8.000000000180123
搜索过程可视化
Java算法代码
import java.util.Arrays;
import java.util.Random;
/**
* @Author：WSKH
* @ClassName：SSA_Solve
* @ClassType：
* @Description：
* @Date：2022/6/8/18:26
* @Email：1187560563@qq.com
* @Blog：https://blog.csdn.net/weixin_51545953?type=blog
*/
public class SSA_Solve {
// 樽海鞘对象
class Salp {
// 当前樽海鞘的坐标（自变量数组）
double[] curVars;
// 当前自变量对应的目标函数值
double curObjValue;
// 适应度（解决最小化问题，所以适应度为目标函数值的倒数）
double fit;
// 全参构造
public Salp(double[] curVars, double curObjValue, double fit) {
this.curVars = curVars;
this.curObjValue = curObjValue;
this.fit = fit;
}
}
// 算法参数
// 变量个数
int varNum = 2;
// 最大迭代次数
int maxGen = 1000;
// 樽海鞘群中樽海鞘的个数
int salpNum = 200;
// 领导者数量和追随者数量（领导者数量+追随者数量=樽海鞘群中樽海鞘的个数）
int leaderNum = 1; // 开始我理解错了，其实领导者只有一个，所以领导者数量设置为1就好
int followNum = salpNum - leaderNum;
// 步长数组（各个维度的步长）
double[] stepArr = new double[]{1.2, 1.2};
// 变量的上下界
double[] ub = new double[]{1000, 1000};
double[] lb = new double[]{-1000, -1000};
// 随机数对象
Random random = new Random();
// 樽海鞘群
Salp[] salps;
// 最佳的樽海鞘
Salp bestSalp;
// 记录迭代过程
public double[][][] positionArr;
// 当前记录的行数
int r;
// 求解主函数
public void solve() {
// 初始化樽海鞘群
initSalps();
// 开始迭代
for (int t = 0; t < maxGen; t++) {
updateLeaderPos(t);
updateFollowPos();
report();
}
// 输出最好的结果
System.out.println("变量取值为：" + Arrays.toString(bestSalp.curVars));
System.out.println("最优解为：" + bestSalp.curObjValue);
}
// 记录
void report() {
for (int i = 0; i < salps.length; i++) {
for (int j = 0; j < varNum; j++) {
positionArr[r][i][j] = salps[i].curVars[j];
}
}
r++;
}
// 更新追随者位置(t：当前迭代次数)
void updateFollowPos(){
for (int i = leaderNum; i < salpNum; i++) {
Salp tempSalp = copySalp(salps[i]);
for (int m = 0; m < varNum; m++) {
double move = 0.5*(tempSalp.curVars[m]+salps[i-1].curVars[m]) - tempSalp.curVars[m];
moveSalp(tempSalp,m,move);
}
updateSalp(tempSalp);
// 不贪心的追随者（只跟着领导走）
salps[i] = tempSalp;
if(salps[i].fit > bestSalp.fit){
bestSalp = copySalp(salps[i]);
}
}
}
// 更新领导者位置 (t；当前迭代次数)
void updateLeaderPos(int t) {
for (int i = 0; i < leaderNum; i++) {
Salp tempSalp = copySalp(salps[i]);
for (int m = 0; m < varNum; m++) {
double c1 = 2 * Math.exp(-(Math.pow(4d * t / (double) maxGen, 2)));
double c2 = (random.nextDouble() - 0.5) * 2;
double c3 = (random.nextDouble() - 0.5) * 2;
double move = 0d;
if (c3 >= 0) {
move = c1 * ((ub[m] - lb[m] * c2 + lb[m]));
} else {
move = -c1 * ((ub[m] - lb[m] * c2 + lb[m]));
}
moveSalp(tempSalp,m,move);
}
updateSalp(tempSalp);
// 贪心的领导（只去往比当前结果好的位置，如果领导不贪心，则不容易收敛，到处跑）
if(tempSalp.fit > salps[i].fit){
salps[i] = tempSalp;
if(salps[i].fit > bestSalp.fit){
bestSalp = copySalp(salps[i]);
}
}
}
}
// 求两个樽海鞘之间的距离
double getDistance(Salp f1, Salp f2) {
double dis = 0d;
for (int i = 0; i < varNum; i++) {
dis += Math.pow(f1.curVars[i] - f2.curVars[i], 2);
}
return Math.sqrt(dis);
}
// 初始化樽海鞘群
private void initSalps() {
positionArr = new double[maxGen][salpNum][varNum];
salps = new Salp[salpNum];
for (int i = 0; i < salpNum; i++) {
salps[i] = getRandomSalp();
if (i == 0 || bestSalp.fit < salps[i].fit) {
bestSalp = copySalp(salps[i]);
}
}
}
// 控制樽海鞘在第m个维度上移动n个距离
public void moveSalp(Salp salp, int m, double n) {
// 移动
salp.curVars[m] += n;
// 超出定义域的判断
if (salp.curVars[m] < lb[m]) {
salp.curVars[m] = lb[m];
}
if (salp.curVars[m] > ub[m]) {
salp.curVars[m] = ub[m];
}
}
// 更新樽海鞘信息
void updateSalp(Salp salp) {
double objValue = getObjValue(salp.curVars);
salp.curObjValue = objValue;
salp.fit = 1 / objValue;
}
// 获取一个随机生成的樽海鞘
Salp getRandomSalp() {
double[] vars = new double[varNum];
for (int j = 0; j < vars.length; j++) {
vars[j] = lb[j] + random.nextDouble() * (ub[j] - lb[j]);
}
double objValue = getObjValue(vars);
return new Salp(vars.clone(), objValue, 1 / objValue);
}
/**
* @param vars 自变量数组
* @return 返回目标函数值
*/
public double getObjValue(double[] vars) {
//目标：在变量区间范围最小化 Z = x^2 + y^2 - xy - 10x - 4y +60
return Math.pow(vars[0], 2) + Math.pow(vars[1], 2) - vars[0] * vars[1] - 10 * vars[0] - 4 * vars[1] + 60;
}
// 复制樽海鞘
Salp copySalp(Salp old) {
return new Salp(old.curVars.clone(), old.curObjValue, old.fit);
}
}
可视化代码
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Button;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.util.Duration;
/**
* @Author：WSKH
* @ClassName：PlotUtil
* @ClassType：
* @Description：
* @Date：2022/6/6/18:31
* @Email：1187560563@qq.com
* @Blog：https://blog.csdn.net/weixin_51545953?type=blog
*/
public class PlotUtil extends Application {
//当前的时间轴
private Timeline nowTimeline;
//绘图位置坐标
private double[][][] positionArr;
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) throws Exception {
// 调用算法获取绘图数据
SSA_Solve solver = new SSA_Solve();
solver.solve();
positionArr = solver.positionArr;
// 画图
try {
BorderPane root = new BorderPane();
root.setStyle("-fx-padding: 20;");
Scene scene = new Scene(root, 1600, 900);
double canvasWid = 800;
double canvasHei = 800;
//根据画布大小缩放坐标值
this.fixPosition(canvasWid - 100, canvasHei - 100);
//画布和画笔
HBox canvasHbox = new HBox();
Canvas canvas = new Canvas();
canvas.setWidth(canvasWid);
canvas.setHeight(canvasHei);
canvasHbox.setPrefWidth(canvasWid);
canvasHbox.getChildren().add(canvas);
canvasHbox.setAlignment(Pos.CENTER);
canvasHbox.setStyle("-fx-spacing: 20;" +
"-fx-background-color: #87e775;");
root.setTop(canvasHbox);
GraphicsContext paintBrush = canvas.getGraphicsContext2D();
//启动
HBox hBox2 = new HBox();
Button beginButton = new Button("播放迭代过程");
hBox2.getChildren().add(beginButton);
root.setBottom(hBox2);
hBox2.setAlignment(Pos.CENTER);
//启动仿真以及暂停仿真
beginButton.addEventHandler(MouseEvent.MOUSE_CLICKED, event -> {
nowTimeline.play();
});
//创建扫描线连接动画
nowTimeline = new Timeline();
createAnimation(paintBrush);
primaryStage.setScene(scene);
primaryStage.show();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 修正cityPositionArr的坐标，让画出来的点在画布内
*
* @param width
* @param height
*/
private void fixPosition(double width, double height) {
double minX = Double.MAX_VALUE;
double maxX = -Double.MAX_VALUE;
double minY = Double.MAX_VALUE;
double maxY = -Double.MAX_VALUE;
for (int i = 0; i < this.positionArr.length; i++) {
for (int j = 0; j < this.positionArr[0].length; j++) {
minX = Math.min(minX, this.positionArr[i][j][0]);
maxX = Math.max(maxX, this.positionArr[i][j][0]);
minY = Math.min(minY, this.positionArr[i][j][1]);
maxY = Math.max(maxY, this.positionArr[i][j][1]);
}
}
double multiple = Math.max((maxX - minX) / width, (maxY - minY) / height);
//转化为正数数
for (int i = 0; i < this.positionArr.length; i++) {
for (int j = 0; j < this.positionArr[0].length; j++) {
if (minX < 0) {
this.positionArr[i][j][0] = this.positionArr[i][j][0] - minX;
}
if (minY < 0) {
this.positionArr[i][j][1] = this.positionArr[i][j][1] - minY;
}
}
}
for (int i = 0; i < this.positionArr.length; i++) {
for (int j = 0; j < this.positionArr[0].length; j++) {
this.positionArr[i][j][0] = this.positionArr[i][j][0] / multiple;
this.positionArr[i][j][1] = this.positionArr[i][j][1] / multiple;
}
}
}
/**
* 用画笔在画布上画出所有的孔
* 画第i代的所有粒子
*/
private void drawAllCircle(GraphicsContext paintBrush, int i) {
paintBrush.clearRect(0, 0, 2000, 2000);
paintBrush.setFill(Color.RED);
for (int j = 0; j < this.positionArr[i].length; j++) {
drawCircle(paintBrush, i, j);
}
}
/**
* 用画笔在画布上画出一个孔
* 画第i代的第j个粒子
*/
private void drawCircle(GraphicsContext paintBrush, int i, int j) {
double x = this.positionArr[i][j][0];
double y = this.positionArr[i][j][1];
double radius = 2;
// 圆的直径
double diameter = radius * 2;
paintBrush.fillOval(x, y, diameter, diameter);
}
/**
* 创建动画
*/
private void createAnimation(GraphicsContext paintBrush) {
for (int i = 0; i < this.positionArr[0].length; i++) {
int finalI = i;
KeyFrame keyFrame = new KeyFrame(Duration.seconds(i * 0.05), event -> drawAllCircle(paintBrush, finalI));
nowTimeline.getKeyFrames().add(keyFrame);
}
}
}