//======================================================= file = hist.c =====
//=  Program to compute the histogram for a series X of size N              =
//===========================================================================
//=  Notes:                                                                 =
//=    1) Input from input file "in.dat" to stdin (see example below)       =
//=        * Comments are bounded by "&" characters at the beginning and    =
//=          end of the comment block                                       =
//=    2) Output is to stdout                                               =
//=    3) Must manually set BUCKET_SIZE and NUM_BUCKET                      =
//=    4) Assumes that minimum value is 0.0                                 =
//=-------------------------------------------------------------------------=
//= Example "in.dat" file:                                                  =
//=                                                                         =
//=    & Sample series of data which can be integers or reals.              =
//=      There are 11 values in this file. &                                =
//=     0.0                                                                 =
//=     2.9                                                                 =
//=     8.9                                                                 =
//=     1.5                                                                 =
//=     0.5                                                                 =
//=     3.1                                                                 =
//=     9.0                                                                 =
//=     4.0                                                                 =
//=    11.5                                                                 =
//=     9.0                                                                 =
//=     0.0                                                                 =
//=-------------------------------------------------------------------------=
//= Example output (for above "in.dat", BUCKET_SIZE = 2.0, NUM_BUCKET = 5)  =
//=                                                                         =
//=   c:\work\hist < in.dat                                                 =
//=   ------------------------------------------------ hist.c -----         =
//=     Frequency for 5 buckets of size 2.000000 (for 11 samples)           =
//=        0.000000000 <= X <    2.000000000 =      4 -- 36.3636 %          =
//=        2.000000000 <= X <    4.000000000 =      2 -- 18.1818 %          =
//=        4.000000000 <= X <    6.000000000 =      1 --  9.0909 %          =
//=        6.000000000 <= X <    8.000000000 =      0 --  0.0000 %          =
//=        8.000000000 <= X <   10.000000000 =      3 -- 27.2727 %          =
//=   -------------------------------------------------------------         =
//=     Not in range =      1 --  9.0909 %                                  =
//=   -------------------------------------------------------------         =
//=-------------------------------------------------------------------------=
//=  Build: gcc hist.c, bcc32 hist.c, cl hist.c                             =
//=-------------------------------------------------------------------------=
//=  Execute: hist < in.dat                                                 =
//=-------------------------------------------------------------------------=
//=  Author: Kenneth J. Christensen                                         =
//=          University of South Florida                                    =
//=          WWW: http://www.csee.usf.edu/~christen                         =
//=          Email: christen@csee.usf.edu                                   =
//=-------------------------------------------------------------------------=
//=  History: KJC (05/11/00) - Genesis                                      =
//===========================================================================

//----- Include files -------------------------------------------------------
#include <stdio.h>                 // Needed for printf() and feof()
#include <stdlib.h>                // Needed for exit(), atof(), and qsort()
#include <string.h>                // Needed for strcmp()

//----- Defines -------------------------------------------------------------
#define MAX_SIZE       2000000     // Maximum size of time series data array
#define BUCKET_SIZE          2     // Bucket size
#define NUM_BUCKET          10     // Number of buckets

//----- Globals -------------------------------------------------------------
double     X[MAX_SIZE];            // Time series read from "in.dat"
long int   N;                      // Number of values in "in.dat"

//----- Function prototypes -------------------------------------------------
void load_X_array(void);                    // Load X array
int  comp(const void *p, const void *q);    // Compare p and q for qsort()

//===========================================================================
//=  Main program                                                           =
//===========================================================================
void main(void)
{
  int i, j;                        // Loop counters
  int count;                       // Frequency counter for this bucket
  int total_count;                 // Total count of all buckets
  int start;                       // Start index for histogram loop

  // Load the series X
  printf("-------------------------------------------------- hist.c -----\n");
  load_X_array();

  // Sort the series X using ANSI C qsort() function
  qsort(X, N, sizeof(double), comp);

  // Output NUM_BUCKETS and BUCKET_SIZE
  printf("  Frequency for %d buckets of size %f (for %d samples) \n",
    NUM_BUCKET, (double) BUCKET_SIZE, N);

  // Do for all the buckets
  total_count = 0;
  start = 0;
  for (i=0; i<NUM_BUCKET; i++)
  {
    // Scan X[] for current bucket size
    count = 0;
    for(j=start; j<N; j++)
    {
      // Count as in this bucket
      if (X[j] < ((i+1) * (double) BUCKET_SIZE))
      {
        count++;
        total_count++;
      }

      // For this case need to start couting for next bucket
      if (X[j] >= ((i+1) * (double) BUCKET_SIZE))
      {
        start = j;
        break;
      }

      // For this case we are all done
      if (j == (N-1))
      {
        start = N;
        break;
      }
    }

    // Output count and percentage for current bucket size
    printf("  %14.9f <= X < %14.9f = %6ld -- %f %% \n",
      (i * (double) BUCKET_SIZE), ((i + 1) * (double) BUCKET_SIZE),
      count, 100.0 * ((double) count / N));
  }

  // Check if any were not counted and output count and percentage
  if (total_count < N)
  {
    printf("---------------------------------------------------------------\n");
    printf("  Not in range = %6d -- %f %% \n",
      (N - total_count), 100.0 * ((double) (N - total_count) / N));
  }
  printf("---------------------------------------------------------------\n");
}

//===========================================================================
//=  Function to load X array from stdin and determine N                    =
//===========================================================================
void load_X_array(void)
{
  char      temp_string[1024];     // Temporary string variable

  // Read all values into X
  N = 0;
  while(1)
  {
    scanf("%s", temp_string);
    if (feof(stdin)) goto end;

    // This handles a comment bounded by "&" symbols
    while (strcmp(temp_string, "&") == 0)
    {
      do
      {
        scanf("%s", temp_string);
        if (feof(stdin)) goto end;
      } while (strcmp(temp_string, "&") != 0);
      scanf("%s", temp_string);
      if (feof(stdin)) goto end;
    }

    // Enter value in array and increment array index
    X[N] = atof(temp_string);
    N++;

    // Check if MAX_SIZE data values exceeded
    if (N >= MAX_SIZE)
    {
      printf("*** ERROR - greater than %ld data values \n", MAX_SIZE);
      exit(1);
    }
  }

  // End-of-file escape
  end:

  return;
}

//===========================================================================
//=  Function to compare two aruguments in an array of double               =
//=   - Needed by qsort()                                                   =
//===========================================================================
int  comp(const void *p, const void *q)
{
  double *ptr1 = (double *)(p);
  double *ptr2 = (double *)(q);

  if (*ptr1 < *ptr2) return -1;
  else if (*ptr1 == *ptr2) return 0;
  else return 1;
}