1 /*
2 * Copyright 2016 E-Tool, Inc.
3 */
4
5 #ifndef distance_h
6 #define distance_h
7 #include <math.h>
8 #include <vector>
9 using std::vector;
10
11 #define max(a,b) (a>b?a:b)
12 #define min(a,b) (a<b?a:b)
13
14 class Distance {
15 public:
16 static double euclidean_distance(double x1,double y1,double x2,double y2) {
17 return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
18 }
19 static double euclidean_distance(double x1, double y1, double z1, double x2, double y2, double z2) {
20 return sqrt((x1 - x2)*(x1 - x2) + (y1 - y2)*(y1 - y2)+(z1-z2)*(z1-z2));
21 }
22 static double euclidean_distance(vector<double> x, vector<double> y) {
23 double result = 0;
24 for (int i = 0;i < x.size();i++) {
25 result += (x[i]-y[i])*(x[i]-y[i]);
26 }
27 return sqrt(result);
28 }
29 static double manhattan_distance(double x1, double y1, double x2, double y2) {
30 return abs(x1 - x2) + abs(y1 - y2);
31 }
32 static double manhattan_distance(vector<double> x, vector<double> y) {
33 double result = 0;
34 for (int i = 0;i < x.size();i++) {
35 result += abs(x[i] - y[i]);
36 }
37 return result;
38 }
39 static double chebyshev_distance(double x1, double y1, double x2, double y2) {
40 return max(abs(x1 - x2) ,abs(y1 - y2));
41 }
42 static double chebyshev_distance(vector<double> x, vector<double> y) {
43 double result=-1;
44 for (int i = 0;i < x.size();i++) {
45 result = max(result, abs(x[i] - y[i]));
46 }
47 return result;
48 }
49 static double minkowski_distance(vector<double> x, vector<double> y,int p) {
50 double result = 0;
51 for (int i = 0;i < x.size();i++) {
52 result += pow(abs(x[i]-y[i]),p);
53 }
54 return pow(result,1/p);
55 }
56 /*
57 * Standardized Euclidean distance
58 */
59 static double standardized_euclidean_distance(vector<double> x, vector<double> y) {
60 double result = 0;
61 for (int i = 0;i < x.size();i++) {
62 double r=(x[i]+y[i])/2;
63 double s = (x[i]-r)*(x[i]-r)+(y[i]-r)*(y[i]-r);
64 result += (x[i]-y[i])*(x[i]-y[i]) / s;
65 }
66 return sqrt(result);
67 }
68 static double information_entropy(vector<double> p) {
69 double result=0;
70 for (int i = 0;i < p.size();i++) {
71 result -= p[i] * (log(p[i])/log(2));
72 }
73 return result;
74 }
75 };
76
77 #endif
