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#include <stdio.h>
#include <time.h>
#include <math.h>
#include "stc/crand.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.
static int compare(cmap_i_value_t *a, cmap_i_value_t *b) {
return c_default_compare(&a->first, &b->first);
}
using_cvec(e, cmap_i_value_t, 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 histogram map
cmap_i mhist = cmap_i_init();
c_forrange (N) {
int index = (int) round( stc64_normalf(&rng, &dist) );
++ cmap_i_emplace(&mhist, index, 0).first->second;
}
// Transfer map to vec and sort it by map keys.
cvec_e vhist = cvec_e_init();
c_foreach (i, cmap_i, mhist)
cvec_e_push_back(&vhist, *i.ref);
cvec_e_sort(&vhist);
// Print the gaussian bar chart
cstr_t bar = cstr_init();
c_foreach (i, cvec_e, vhist) {
size_t n = (size_t) (i.ref->second * StdDev * Scale * 2.5 / N);
if (n > 0) {
cstr_resize(&bar, n, '*');
printf("%4d %s\n", i.ref->first, bar.str);
}
}
// Cleanup
cstr_del(&bar);
cmap_i_del(&mhist);
cvec_e_del(&vhist);
}
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