用java写一个frechet距离算法
时间: 2024-03-11 18:43:44 浏览: 76
以下是Java实现的Frechet距离算法:
```java
public class FrechetDistance {
public static double compute(double[][] P, double[][] Q) {
int m = P.length;
int n = Q.length;
double[][] C = new double[m][n];
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
double dist = distance(P[i], Q[j]);
if (i == 0 && j == 0) {
C[i][j] = dist;
} else if (i == 0) {
C[i][j] = Math.max(C[i][j - 1], dist);
} else if (j == 0) {
C[i][j] = Math.max(C[i - 1][j], dist);
} else {
C[i][j] = Math.max(Math.min(Math.min(C[i - 1][j], C[i][j - 1]), C[i - 1][j - 1]), dist);
}
}
}
return C[m - 1][n - 1];
}
private static double distance(double[] a, double[] b) {
double dx = a[0] - b[0];
double dy = a[1] - b[1];
return Math.sqrt(dx * dx + dy * dy);
}
public static void main(String[] args) {
double[][] P = {{1, 1}, {2, 2}, {3, 3}};
double[][] Q = {{2, 2}, {3, 3}, {4, 4}};
double dist = compute(P, Q);
System.out.println("Frechet distance: " + dist);
}
}
```
这个算法输入两个数组P和Q,每个数组包含一些二维点的坐标。输出是P和Q之间的Frechet距离。实现中使用了一个二维数组C来存储动态规划的中间结果。其中C[i][j]表示P的前i个点和Q的前j个点之间的Frechet距离。
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