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statistc.cpp File Reference
#include "mfcpch.h"
#include "statistc.h"
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include "helpers.h"
#include "scrollview.h"
#include "tprintf.h"

Go to the source code of this file.

Functions

inT32 choose_nth_item (inT32 index, float *array, inT32 count)
inT32 choose_nth_item (inT32 index, void *array, inT32 count, size_t size, int(*compar)(const void *, const void *))
void swap_entries (void *array, size_t size, inT32 index1, inT32 index2)

Function Documentation

inT32 choose_nth_item ( inT32  index,
float *  array,
inT32  count 
)

Definition at line 550 of file statistc.cpp.

{
inT32 next_sample; // next one to do
inT32 next_lesser; // space for new
inT32 prev_greater; // last one saved
inT32 equal_count; // no of equal ones
float pivot; // proposed median
float sample; // current sample
if (count <= 1)
return 0;
if (count == 2) {
if (array[0] < array[1]) {
return index >= 1 ? 1 : 0;
}
else {
return index >= 1 ? 0 : 1;
}
}
else {
if (index < 0)
index = 0; // ensure legal
else if (index >= count)
index = count - 1;
equal_count = (inT32) (rand() % count);
pivot = array[equal_count];
// fill gap
array[equal_count] = array[0];
next_lesser = 0;
prev_greater = count;
equal_count = 1;
for (next_sample = 1; next_sample < prev_greater;) {
sample = array[next_sample];
if (sample < pivot) {
// shuffle
array[next_lesser++] = sample;
next_sample++;
}
else if (sample > pivot) {
prev_greater--;
// juggle
array[next_sample] = array[prev_greater];
array[prev_greater] = sample;
}
else {
equal_count++;
next_sample++;
}
}
for (next_sample = next_lesser; next_sample < prev_greater;)
array[next_sample++] = pivot;
if (index < next_lesser)
return choose_nth_item (index, array, next_lesser);
else if (index < prev_greater)
return next_lesser; // in equal bracket
else
return choose_nth_item (index - prev_greater,
array + prev_greater,
count - prev_greater) + prev_greater;
}
}
inT32 choose_nth_item ( inT32  index,
void *  array,
inT32  count,
size_t  size,
int(*)(const void *, const void *)  compar 
)

Definition at line 617 of file statistc.cpp.

{
int result; // of compar
inT32 next_sample; // next one to do
inT32 next_lesser; // space for new
inT32 prev_greater; // last one saved
inT32 equal_count; // no of equal ones
inT32 pivot; // proposed median
if (count <= 1)
return 0;
if (count == 2) {
if (compar (array, (char *) array + size) < 0) {
return index >= 1 ? 1 : 0;
}
else {
return index >= 1 ? 0 : 1;
}
}
if (index < 0)
index = 0; // ensure legal
else if (index >= count)
index = count - 1;
pivot = (inT32) (rand () % count);
swap_entries (array, size, pivot, 0);
next_lesser = 0;
prev_greater = count;
equal_count = 1;
for (next_sample = 1; next_sample < prev_greater;) {
result =
compar ((char *) array + size * next_sample,
(char *) array + size * next_lesser);
if (result < 0) {
swap_entries (array, size, next_lesser++, next_sample++);
// shuffle
}
else if (result > 0) {
prev_greater--;
swap_entries(array, size, prev_greater, next_sample);
}
else {
equal_count++;
next_sample++;
}
}
if (index < next_lesser)
return choose_nth_item (index, array, next_lesser, size, compar);
else if (index < prev_greater)
return next_lesser; // in equal bracket
else
return choose_nth_item (index - prev_greater,
(char *) array + size * prev_greater,
count - prev_greater, size,
compar) + prev_greater;
}
void swap_entries ( void *  array,
size_t  size,
inT32  index1,
inT32  index2 
)

Definition at line 678 of file statistc.cpp.

{
char tmp;
char *ptr1; // to entries
char *ptr2;
size_t count; // of bytes
ptr1 = reinterpret_cast<char*>(array) + index1 * size;
ptr2 = reinterpret_cast<char*>(array) + index2 * size;
for (count = 0; count < size; count++) {
tmp = *ptr1;
*ptr1++ = *ptr2;
*ptr2++ = tmp; // tedious!
}
}