1 #include<math.h>
2 #include<stdio.h>
3 #include<stdlib.h>
4 #include<iostream>
5 using namespace std;
6 void kmeans(int n, float* xy, int k, float* cxy)
7 {
8 int i,j;
9 for(i=0;i<k;i++)
10 {
11 cxy[2*i]=xy[2*i];
12 cxy[2*i+1]=xy[2*i+1];
13 }
14
15 int* mindis=(int*)malloc(n*sizeof(int));
16 int* premindis=(int*)malloc(n*sizeof(int));
17 for(i=0;i<n;i++)
18 {
19 mindis[i]=-1;
20 }
21 int change=1;
22
23 while(change)
24 {
25 for(i=0;i<n;i++)
26 {
27 premindis[i]=mindis[i];
28 }
29 for(i=0;i<n;i++)
30 {
31 float min=9999;
32 for(j=0;j<k;j++)
33 {
34 double s=sqrt((xy[2*i]-cxy[2*j])*(xy[2*i]-cxy[2*j])+(xy[2*i+1]-cxy[2*j+1])*(xy[2*i+1]-cxy[2*j+1]));
35 if(s<min)
36 {
37 min=s;
38 mindis[i]=j;
39 }
40 }
41 }
42
43 /*
44 for(i=0;i<2;i++)
45 {
46 printf("%.3f ",cxy[2*i]);
47 printf("%.3f\n",cxy[2*i+1]);
48 }
49 */
50
51 for(i=0;i<k;i++)
52 {
53 int num=0;
54 float s0=0.0;
55 float s1=0.0;
56 //cout<<i<<":";
57 for(j=0;j<n;j++)
58 {
59 if(mindis[j]==i)
60 {
61 num++;
62 //cout<<j<<" ";
63 s0+=xy[2*j];
64 s1+=xy[2*j+1];
65 }
66 }
67 if(num)
68 {
69 cxy[2*i]=s0/num;
70 cxy[2*i+1]=s1/num;
71 }
72 //cout<<endl;
73 }
74 int flag=0;
75 for(i=0;i<n;i++)
76 {
77 if(mindis[i]!=premindis[i])
78 {
79 flag=1;
80 break;
81 }
82 }
83 if(flag==0)
84 change=0;
85 }
86
87
88 }
89 int main()
90 {
91 float xy[12]={1.0, 1.0, 2.0, 1.0, 1.0, 2.0, 4.0, 5.0, 5.0, 4.0, 4.0, 4.0};
92 float cxy[4]={0.0, 0.0, 0.0, 0.0};
93 kmeans(6,xy,2,cxy);
94 int i;
95 for(i=0;i<2;i++)
96 {
97 printf("%.3f ",cxy[2*i]);
98 printf("%.3f\n",cxy[2*i+1]);
99 }
100 return 0;
101 }
