用c语言实现dbscan算法

DBSCAN算法是一种基于密度的聚类算法，可以用于发现任意形状的簇。以下是用C语言实现DBSCAN算法的代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define MAX_POINTS 1000

typedef struct {
    double x, y;
} Point;

typedef struct {
    int id;
    int is_core;
    int cluster_id;
} PointInfo;

int num_points;
Point points[MAX_POINTS];
PointInfo point_info[MAX_POINTS];

double eps;
int min_pts;

double distance(Point p1, Point p2) {
    double dx = p1.x - p2.x;
    double dy = p1.y - p2.y;
    return sqrt(dx * dx + dy * dy);
}

int region_query(int p) {
    int count = 0;
    for (int i = 0; i < num_points; i++) {
        if (i == p) continue;
        if (distance(points[p], points[i]) <= eps) {
            count++;
        }
    }
    return count;
}

void expand_cluster(int p, int cluster_id) {
    point_info[p].cluster_id = cluster_id;
    int neighbor_pts[MAX_POINTS];
    int num_neighbors = 0;
    for (int i = 0; i < num_points; i++) {
        if (i == p) continue;
        if (distance(points[p], points[i]) <= eps) {
            neighbor_pts[num_neighbors++] = i;
        }
    }
    if (num_neighbors >= min_pts) {
        point_info[p].is_core = 1;
        for (int i = 0; i < num_neighbors; i++) {
            int q = neighbor_pts[i];
            if (point_info[q].cluster_id == -1) {
                expand_cluster(q, cluster_id);
            }
        }
    }
}

void dbscan() {
    int cluster_id = 0;
    for (int i = 0; i < num_points; i++) {
        if (point_info[i].cluster_id != -1) continue;
        if (region_query(i) >= min_pts) {
            point_info[i].is_core = 1;
            expand_cluster(i, cluster_id);
            cluster_id++;
        } else {
            point_info[i].is_core = 0;
        }
    }
}

int main() {
    // Read input data
    scanf("%d %lf %d", &num_points, &eps, &min_pts);
    for (int i = 0; i < num_points; i++) {
        scanf("%lf %lf", &points[i].x, &points[i].y);
        point_info[i].id = i;
        point_info[i].is_core = -1;
        point_info[i].cluster_id = -1;
    }

    // Run DBSCAN algorithm
    dbscan();

    // Print results
    for (int i = 0; i < num_points; i++) {
        printf("%d %d\n", point_info[i].id, point_info[i].cluster_id);
    }

    return 0;
}

该代码实现了一个简单的DBSCAN算法，可以读入点集数据并输出每个点所属的簇的编号。