// Fig. 4.17: fig04_17.cpp
// This program introduces the topic of survey data analysis.
// It computes the mean, median, and mode of the data.
#include <iostream>
  
using std::cout;
using std::endl;
using std::fixed;
using std::showpoint;
 
#include <iomanip>
 
using std::setw;
using std::setprecision;
 
void mean( const int [], int );
void median( int [], int );
void mode( int [], int [], int );
void bubbleSort( int[], int );
void printArray( const int[], int );
 
int main()
{
  const int responseSize = 99;  // size of array responses
 
  int frequency[ 10 ] = { 0 };  // initialize array frequency
 
  // initialize array responses
  int response[ responseSize ] =  
    { 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 };
 
  // process responses
  mean( response, responseSize );
  median( response, responseSize );
  mode( frequency, response, responseSize );
 
  return 0;  // indicates successful termination
 
} // end main
 
// calculate average of all response values
void mean( const int answer[], int arraySize )
{
  int total = 0;
 
  cout << "********\n  Mean\n********\n";
 
  // total response values
  for ( int i = 0; i < arraySize; i++ )
    total += answer[ i ];
 
  // format and output results
  cout << fixed << setprecision( 4 );
 
  cout << "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 (" << arraySize 
       << "). The mean value for\nthis run is: " 
       << total << " / " << arraySize << " = "
       << static_cast< double >( total ) / arraySize 
       << "\n\n";
 
} // end function mean
 
// sort array and determine median element's value
void median( int answer[], int size )
{
  cout << "\n********\n Median\n********\n"
       << "The unsorted array of responses is";
 
  printArray( answer, size );  // output unsorted array
 
  bubbleSort( answer, size );  // sort array
 
  cout << "\n\nThe sorted array is";
  printArray( answer, size );  // output sorted array 
     
  // display median element
  cout << "\n\nThe median is element " << size / 2
       << " of\nthe sorted " << size 
       << " element array.\nFor this run the median is "
       << answer[ size / 2 ] << "\n\n";
 
} // end function median
 
// determine most frequent response
void mode( int freq[], int answer[], int size )
{
  int largest = 0;    // represents largest frequency
  int modeValue = 0;  // represents most frequent response

  cout << "\n********\n  Mode\n********\n";

  // initialize frequencies to 0
  for ( int i = 1; i <= 9; i++ )
    freq[ i ] = 0;

  // summarize frequencies
  for ( int j = 0; j < size; j++ )
    ++freq[ answer[ j ] ];

  // output headers for result columns
  cout << "Response" << setw( 11 ) << "Frequency"
       << setw( 19 ) << "Histogram\n\n" << setw( 55 )
       << "1    1    2    2\n" << setw( 56 )
       << "5    0    5    0    5\n\n";

  // output results
  for ( int rating = 1; rating <= 9; rating++ ) {
    cout << setw( 8 ) << rating << setw( 11 )
	 << freq[ rating ] << "          ";

    // keep track of mode value and largest fequency value
    if ( freq[ rating ] > largest ) {                     
      largest = freq[ rating ];                          
      modeValue = rating;                                
                                                            
    } // end if                                           

      // output histogram bar representing frequency value
    for ( int k = 1; k <= freq[ rating ]; k++ )
      cout << '*';

    cout << '\n';  // begin new line of output

  } // end outer for

  // display the mode value
  cout << "The mode is the most frequent value.\n"
       << "For this run the mode is " << modeValue
       << " which occurred " << largest << " times." << endl;

} // end function mode

// function that sorts an array with bubble sort algorithm
void bubbleSort( int a[], int size )
{
  int hold;  // temporary location used to swap elements

  // loop to control number of passes
  for ( int pass = 1; pass < size; pass++ )

    // loop to control number of comparisons per pass
    for ( int j = 0; j < size - 1; j++ )

      // swap elements if out of order
      if ( a[ j ] > a[ j + 1 ] ) {
	hold = a[ j ];
	a[ j ] = a[ j + 1 ];
	a[ j + 1 ] = hold;

      } // end if

} // end function bubbleSort

// output array contents (20 values per row)
void printArray( const int a[], int size )
{
  for ( int i = 0; i < size; i++ ) {

    if ( i % 20 == 0 )  // begin new line every 20 values
      cout << endl;

    cout << setw( 2 ) << a[ i ];

  } // end for

} // end function printArray