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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.
static int compare(cmap_i_entry_t *a, cmap_i_entry_t *b) {
return c_default_compare(&a->first, &b->first);
}
// Vector: typetag 'e' for (map) entry
using_cvec(e, cmap_i_entry_t, c_default_destroy, compare);
int main()
{
enum {N = 10000000};
const double Mean = -12.0, StdDev = 8.0, Mag = 12000.0 / StdDev;
printf("Demo of gaussian / normal distribution of %d random samples\n", N);
// Setup random engine with normal distribution.
uint64_t seed = time(NULL);
crand_rng64_t rng = crand_rng64_init(seed);
crand_normal_f64_t dist = crand_normal_f64_init(Mean, StdDev);
// Create histogram map
cmap_i mhist = cmap_ini;
for (size_t i = 0; i < N; ++i) {
int index = (int) round( crand_normal_f64(&rng, &dist) );
cmap_i_emplace(&mhist, index, 0).first->second += 1;
}
// Transfer map to vec and sort it by map keys.
cvec_e vhist = cvec_ini;
c_foreach (i, cmap_i, mhist)
cvec_e_push_back(&vhist, *i.get);
cvec_e_sort(&vhist);
// Print the gaussian bar chart
cstr_t bar = cstr_ini;
c_foreach (i, cvec_e, vhist) {
size_t n = (size_t) (i.get->second * Mag / N);
if (n > 0) {
// bar string: take ownership in new str after freeing current.
cstr_take(&bar, cstr_with_size(n, '*'));
printf("%4d %s\n", i.get->first, bar.str);
}
}
// Cleanup
cstr_destroy(&bar);
cmap_i_destroy(&mhist);
cvec_e_destroy(&vhist);
}
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