/* DataSet.c
   Implementation of a DataSet Class
   [Taken from requirements .....]
   Author: J Morris
   Date Last Modified: 17 October, 1997
*/

#include <stdlib.h>
#include <assert.h>

#include "Boolean.h"

struct dataset {
  int max_items;
  int cnt;
  double *data;
  };

#include "DataSet.h"

DataSet ConsDataSet( int max_items ) {
/* Construct a new data set -
   max_items is the maximum number of points in the data set
   Pre-cond: max_items > 0
   Post-cond: returns a newly constructed DataSet 
               or
              NULL if insufficient memory
*/
	DataSet ds;
  assert( max_items > 0 );
  ds = malloc( sizeof( struct dataset ) );
  if ( ds != NULL ) {
    ds->max_items = max_items;
    ds->cnt = 0;
    ds->data = malloc( max_items*sizeof( double ) );
    if ( ds->data == NULL ) {
      free( ds );
      ds = NULL;
      }
    }
  return NULL;
  } 


int DeleteDataSet( DataSet ds ) {
/* Delete a data set.
   Pre-cond: ds is a valid DataSet
   Post-cond: space used by ds has been freed
              returns TRUE if no errors, FALSE on error
*/
  assert( ds != NULL );
  assert( ds->data != NULL );
  free( ds->data );
  free( ds );
  return TRUE;
  }

int ClearDataSet( DataSet ds ) {
/* Reset the DataSet ds
   (allows the same space to be re-used, without 
    free/malloc overhead)
   Pre-cond: ds is a valid DataSet
   Post-cond: entries in ds have all been cleared,
*/
  assert( ds != NULL );
  assert( ds->data != NULL );

	ds->cnt = 0;
  return TRUE;
  }

int TotalPoints( DataSet ds ) {
/* Count total points in the data set
   Pre-cond: ds is a valid DataSet
   Post-cond: returns count of points added to the DataSet
*/
	assert( ds != NULL );
	return ds->cnt;
  }

int AddDatum( DataSet ds, double x ) {
	assert( ds != NULL );
	if ( ds->cnt >= ds->max_items ) return FALSE;
	ds->data[ds->cnt] = x;
	ds->cnt++;
	return TRUE;
  }

   
double Maximum( DataSet ds, int *index ) {
	int j, k;
	double max;
	assert( ds != NULL );
	
	if ( ds->cnt == 0 ) {
		*index = -1;
		return 0.0;
		}
	max = ds->data[0];
	k = 0;
	for(j=1; j<ds->cnt; j++ ) {
		if ( ds->data[j] > max ) {
			max = ds->data[j];
			k = j;
			}
		}
	*index = k;	
	return max;
  }
  
  
double Minimum( DataSet ds, int *index ) {
	int j, k;
	double min;
	assert( ds != NULL );
	
	if ( ds->cnt == 0 ) {
		*index = -1;
		return 0.0;
		}
	min = ds->data[0];
	k = 0;
	for(j=1; j<ds->cnt; j++ ) {
		if ( ds->data[j] < min ) {
			min = ds->data[j];
			k = j;
			}
		}
	*index = k;	
	return min;
  }

double SampleMean( DataSet ds, int *num_below ) {
	int k, cnt;
	double sum, mean;
	assert( ds != NULL );
	assert( num_below != NULL );

	if ( ds->cnt == 0 ) {
		*num_below = 0;
		return 0.0;
		}

	sum = 0.0;
	for(k=0;k<ds->cnt;k++) {
		sum = sum + ds->data[k];
		}
	mean = sum / ds->cnt;

	cnt = 0;
	for( k=0;k<ds->cnt;k++) {
		if ( ds->data[k] < mean ) cnt++;
		}
	*num_below = cnt;
	return mean;
	}