/* This program introduces the topic of survey data analysis. 
   It computes the mean, median, and  mode of the data */
#include <stdio.h>
#define SIZE 99

void mean(int []);
void median(int []);
void mode(int [], int []);
void bubbleSort(int[]);
void printArray(int[]);

main()
{
   int frequency[10] = {0},
       response[SIZE] = {6, 7, 8, 9, 8, 7, 8, 9, 8, 9,
                         7, 8, 9, 5, 9, 8, 7, 8, 7, 8,
                         6, 7, 8, 9, 3, 9, 8, 7, 8, 7,
                         7, 8, 9, 8, 9, 8, 9, 7, 8, 9,
                         6, 7, 8, 7, 8, 7, 9, 8, 9, 2,
                         7, 8, 9, 8, 9, 8, 9, 7, 5, 3,
                         5, 6, 7, 2, 5, 3, 9, 4, 6, 4,
                         7, 8, 9, 6, 8, 7, 8, 9, 7, 8,
                         7, 4, 4, 2, 5, 3, 8, 7, 5, 6,
                         4, 5, 6, 1, 6, 5, 7, 8, 7};
   mean(response);
   median(response);
   mode(frequency, response);
   return 0;
}

void mean(int answer[])
{
   int j, total = 0;

   printf("%s\n%s\n%s\n", "********", "  Mean", "********");

   for (j = 0; j <= SIZE - 1; j++)
      total += answer[j];

   printf("The mean is the average value of the data\n"
          "items. The mean is equal to the total of\n"
          "all the data items divided by the number\n"
          "of data items (%d). The mean value for\n"
          "this run is: %d / %d = %.4f\n\n",
          SIZE, total, SIZE, (float) total / SIZE);
}

void median(int answer[])
{
   printf("\n%s\n%s\n%s\n%s", 
          "********", " Median", "********", 
          "The unsorted array of responses is");

   printArray(answer);
   bubbleSort(answer);
   printf("\n\nThe sorted array is");
   printArray(answer);
   printf("\n\nThe median is element %d of\n"
          "the sorted %d element array.\n"
          "For this run the median is %d\n\n",
          SIZE / 2, SIZE, answer[SIZE / 2]);
}

void mode(int freq[], int answer[])
{
   int rating, j, h, largest = 0, modeValue = 0;

   printf("\n%s\n%s\n%s\n", 
          "********", "  Mode", "********");

   for (rating = 1; rating <= 9; rating++)
      freq[rating] = 0;

   for (j = 0; j <= SIZE - 1; j++)
      ++freq[answer[j]];

   printf("%s%11s%19s\n\n\n",
          "Response", "Frequency", "Histogram");
   /*printf("%s%11s%19s\n\n%54s\n%54s\n\n",
          "Response", "Frequency", "Histogram",
          "1    1    2    2", "5    0    5    0    5");*/

   for (rating = 1; rating <= 9; rating++) {
      printf("%8d%11d          ", rating, freq[rating]);

      if (freq[rating] > largest) {
         largest = freq[rating];
         modeValue = rating;
      }

      for (h = 1; h <= freq[rating]; h++)
         printf("*");

      printf("\n");
   }

   printf("The mode is the most frequent value.\n"
          "For this run the mode is %d which occurred"
          " %d times.\n", modeValue, largest);
}

void bubbleSort(int a[])
{
   int pass, j, hold;

   for (pass = 1; pass <= SIZE - 1; pass++)

      for (j = 0; j <= SIZE - 2; j++)

         if (a[j] > a[j+1]) {
            hold = a[j];
            a[j] = a[j+1];
            a[j+1] = hold;
         }
}

void printArray(int a[])
{
   int j;

   for (j = 0; j <= SIZE - 1; j++) {

      if (j % 20 == 0)
         printf("\n");

      printf("%2d", a[j]);
   }
}