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#include <stdio.h>
#include <time.h>
#include <math.h>
#include <stc/crandom.h>
#include <stc/cstr.h>
#include <stc/cmap.h>
#include <stc/cvec.h>
// Declare int -> int hashmap. Uses typetag 'i' for ints.
using_cmap(i, int, size_t);
// Declare int vector with map entries that can be sorted by map keys.
typedef struct {int first; size_t second;} mapval;
static int compare(mapval *a, mapval *b) {
return c_default_compare(&a->first, &b->first);
}
using_cvec(e, mapval, compare);
int main()
{
enum {N = 10000000};
const double Mean = -12.0, StdDev = 6.0, Scale = 74;
printf("Demo of gaussian / normal distribution of %d random samples\n", N);
// Setup random engine with normal distribution.
uint64_t seed = time(NULL);
stc64_t rng = stc64_init(seed);
stc64_normalf_t dist = stc64_normalf_init(Mean, StdDev);
// Create and init histogram vec and map with defered destructors:
c_forvar (cvec_e vhist = cvec_e_init(), cvec_e_del(&vhist))
c_forvar (cmap_i mhist = cmap_i_init(), cmap_i_del(&mhist))
{
c_forrange (N) {
int index = (int) round( stc64_normalf(&rng, &dist) );
cmap_i_emplace(&mhist, index, 0).ref->second += 1;
}
// Transfer map to vec and sort it by map keys.
c_foreach (i, cmap_i, mhist)
cvec_e_push_back(&vhist, c_make(mapval){i.ref->first, i.ref->second});
cvec_e_sort(&vhist);
// Print the gaussian bar chart
c_forvar (cstr bar = cstr_null, cstr_del(&bar))
c_foreach (i, cvec_e, vhist) {
size_t n = (size_t) (i.ref->second * StdDev * Scale * 2.5 / (float)N);
if (n > 0) {
cstr_resize(&bar, n, '*');
printf("%4d %s\n", i.ref->first, bar.str);
}
}
}
}
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