Find Median of 1D Array Using Functions in C

The midway value that splits the items into two portions with an equal number of items on either side is known as the median if the list's contents are ordered in order. Even numbers of things have two middle values, while odd numbers of items have just one. Therefore, the median is defined as the average of the two middle values when there are even numbers of elements.

Algorithm

To determine the median, use the procedure below.

First, read the items into an array while maintaining an item count.
The objects are sorted in step two by increasing value.
Calculate the median.

Following is the reasoning behind sorting the data before determining a median:-

for(i=1 ; i <= n-1 ; i++) {
   for (j=1 ; j <= n-i ; j++) {
      if ( a[j] <= a [j+1] ) {
         t = a[j];
         a[j] = a[j+1];
         a[j+1] = t;
      } else
      continue;
   }
}

The following reasoning was used to determine the list's median:-

if ( n % 2 = = 0 )
   median = ( a [ n / 2 ] + a [ n / 2 + 1 ] ) / 2 . 0 ;
else
   median = a [ n / 2 + 1 ] ;

Example: C program to determine the median of supplied integers is provided below.

#include < stdio.h >
#include < conio.h >
#include < sdtlib >
#define N 10
main ( ) {
   int i , j , n ;
   float median , a [ N ] , t ;
   printf ( " ?nter the number of items \ n " ) ;
   scanf ( " % d " , & n ) ;
   /* Reading items into array a */
   printf ( " Input % d values \ n " , n ) ;
   for ( i = 1 ; i < = n ; i + + )
   scanf ( " % f " , & a [ i ] ) ;
   /* Sorting begins */
   for ( i = 1 ; i < = n - 1 ; i + + ) { / * Trip - i begins * /
      for ( j = 1 ; j < = n - i ; j + + ) {
         if ( a [ j ] < = a [ j + 1 ] ) { / * Interchanging values * /
            t = a [ j ] ;
            a [ j ] = a [ j + 1 ] ;
            a [ j + 1 ] = t ;
         }
         else
         continue ;
      }
   } / * sorting ends * /
   / * calculation of median * /
   if ( n % 2 = = 0 )
      median = ( a [ n / 2 ] + a [ n / 2 + 1 ] ) / 2.0 ;
   else
   median = a [ n / 2 + 1 ] ;
   / * Printing * /
   for ( i = 1 ; i < = n ; i + + )
   printf ( " % f " , a [ i ] ) ;
   printf ( " \ n \ n Median is % f \ n " , median ) ;
}

Output:

?nter the number of items
5
Input 5 values
2.3
1.2
3.8
4.6
8.9
8.900000 4.600000 3.800000 2.300000 1.200000
Median is 3.800000
.......................................................
Process executed in 1.22 seconds
Press any Key to continue.

Explanation

In the above example of a program in C++, we have demonstrated how we can find the median of the supplied intergers.

Another Example:

#include < stdio.h >
void swap ( int * p , int * q ) {
   int t ; 
   t = * p ; 
   * p = * q ; 
   * q = t ;
}
void sort ( int a [ ] , int n ) { 
   int i , j , temp ; 
   for ( i = 0 ; i < n - 1 ; i + + ) {
      for ( j = 0 ; j < n - i - 1 ; j + + ) {
         if ( a [ j ] > a [ j + 1 ] )
            swap ( & a [ j ] , & a [ j + 1 ] ) ;
      }
   }
}
int main ( ) {
   int a [ ] = { 6 , 3 , 8 , 5 , 1 } ;
   int n = 5 ;
   int sum , i ; 
   sort ( a , n ) ; 
   n = ( n + 1 ) / 2 - 1 ;      // -1 as array indexing in C starts from 0
   printf ( " Median = % d " , a [ n ] ) ;
   return 0 ;
}

Output:

Median = 5
..................................
Process executed in 1.11 seconds 
Press any key to continue.

Explanation

In the above example of a program in C, Take the list 3, 5, 2, 7, 3 as an example for our input list. First, we reorder it as 2, 3, 3, 5, 7 to determine the median and we discover that ((5+1)/2) is 3 at position 3. Therefore, the median value in this list is 3.

Next TopicFind Reverse of an Array in C Using Functions

← prev next →