Implementation of K-Nearest Neighbors Algorithm in C++

#include<iostream.h>

#include<conio.h>

void main() {
  int i, j, l;
  int tsc = 12;
  char gen[12] = {
    'F',
    'M',
    'F',
    'F',
    'F',
    'M',
    'F',
    'M',
    'M',
    'F',
    'M',
    'F'
  };
  float h[12] = {
    1.6 f,
    2.0 f,
    1.9 f,
    1.88 f,
    1.7 f,
    1.85 f,
    1.6 f,
    1.7 f,
    2.2 f,
    1.8 f,
    1.95 f,
    1.9 f
  };
  char op[12][10] = {
    "short",
    "tall",
    "medium",
    "medium",
    "short",
    "medium",
    "short",
    "short",
    "tall",
    "medium",
    "medium",
    "medium"
  };

  cout << "\n Initial Set:";
  cout << "\nGender\tHeight\tOutput";
  for (i = 0; i < 12; i++) {
    cout << "\n" << gen[i] << "\t" << h[i] << "\t" << op[i];
  }

  float nh;
  char ng;
  cout << "\n Enter tuple to be processed (Height,Gender) :";
  cin >> nh >> ng;

  int t;
  cout << "\n Enter threshold:";
  cin >> t;

  float d[12][2], k;

  //calculating distance to each value in training set
  for (i = 0; i < 12; i++) {
    d[i][0] = i;
    k = h[i] - nh;
    if (k < 0) {
      d[i][1] = -k;
    } else {
      d[i][1] = k;
    }
  }

  //Sorting
  for (i = 0; i < 11; i++) {
    for (j = 0; j < 11; j++) {
      if (d[j][1] > d[j + 1][1]) {
        k = d[j][1];
        d[j][1] = d[j + 1][1];
        d[j + 1][1] = k;

        l = d[j][0];
        d[j][0] = d[j + 1][0];
        d[j + 1][0] = l;
      }
    }
  }

  int nos = 0; //no of shorts
  int nom = 0; //no of mediums
  int not = 0; //no of talls

  cout << "\nGender\tHeight\tOutput\n";
  for (i = 0; i < t; i++) {
    l = d[i][0];
    cout << gen[l] << "\t" << h[l] << "\t" << op[l] << "\n";
    if (strcmp(op[l], "short") == 0) {
      nos++;
    }
    if (strcmp(op[l], "medium") == 0) {
      nom++;
    }
    if (strcmp(op[l], "tall") == 0) {
      not++;
    }
  }

  cout << "\n No of shorts:" << nos;
  cout << "\n No of medium:" << nom;
  cout << "\n No of tall:" << not;

  if (nos > nom &amp;&amp; nos > not) {
    cout << "\n New Tuple is classified as Short";
  }

  if (nom > nos &amp;&amp; nom > not) {
    cout << "\n New Tuple is classified as Medium";
  }

  if (not > nom &amp;&amp; not > nos) {
    cout << "\n New Tuple is classified as Tall";
  }

  getch();
}

/* OUTPUT


 Initial Set:
Gender  Height  Output
F       1.6     short
M       2       tall
F       1.9     medium
F       1.88    medium
F       1.7     short
M       1.85    medium
F       1.6     short
M       1.7     short
M       2.2     tall
F       1.8     medium
M       1.95    medium
F       1.9     medium
 Enter tuple to be processed (Height,Gender) :1.7 M

 Enter threshold:5

Gender  Height  Output
F       1.7     short
M       1.7     short
F       1.8     medium
F       1.6     short
F       1.6     short

 No of shorts:4
 No of medium:1
 No of tall:0
 New Tuple is classified as Short

*/

6 thoughts on “Implementation of K-Nearest Neighbors Algorithm in C++”

  1. this program is showing the error
    ” fatal error: iostream.h: No such file or directory
    compilation terminated.
    “what should i do?

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