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#include <time.h>
#include <stdlib.h>
#include <cairo.h>
#include <math.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
static double
sample_exp (double lambda)
{
double u = drand48 ();
return -log (1 - u) / lambda;
}
#define FALSE 0
#define TRUE 1
#define WIDTH 6000
#define HEIGHT 20
#define N_YEARS 10
#define DEATHS_PER_YEAR 10
#define BG_COLOR 1, 1, 1
#define CLUSTER_WIDTH 10.0
#define CLUSTER_COLOR 0.0, 0.6, 0.3, 0.4
#define LINE_WIDTH 1.0
#define LINE_COLOR 0.0, 0.0, 0.0
#define DEATH_WIDTH 1.0
#define DEATH_COLOR 0.0, 0.0, 0.0
#define DEATH_HEIGHT (CLUSTER_WIDTH / HEIGHT)
static double *
generate_deaths (int n_years, double deaths_per_year, int *n_deaths)
{
double w;
double t;
double *result = malloc (10 * sizeof (double));
double *first;
t = 0.0;
*n_deaths = 0;
w = sample_exp (deaths_per_year);
t += w;
while (t < n_years)
{
result[(*n_deaths)++] = t;
result = realloc (result, ((*n_deaths) + 10) * sizeof (double));
w = sample_exp (deaths_per_year);
t += w;
}
return result;
}
int
main ()
{
cairo_surface_t *surface =
cairo_image_surface_create (CAIRO_FORMAT_ARGB32, WIDTH, HEIGHT);
int i;
double t = 0.0;
cairo_t *cr = cairo_create (surface);
double y = HEIGHT / 2.0;
double w;
int n_deaths;
int cluster;
double *deaths;
int in_cluster;
double cluster_x0;
srand48 (time (0));
deaths = generate_deaths (N_YEARS, DEATHS_PER_YEAR, &n_deaths);
cairo_set_source_rgb (cr, BG_COLOR);
cairo_paint (cr);
cairo_move_to (cr, 0.0, y);
for (i = 1; i < n_deaths; ++i)
{
double d0 = deaths[i - 1];
double d1 = deaths[i];
double x0 = (d0 / N_YEARS) * WIDTH;
double x1 = (d1 / N_YEARS) * WIDTH;
cairo_set_line_width (cr, LINE_WIDTH);
cairo_set_source_rgb (cr, LINE_COLOR);
cairo_move_to (cr, x0, y);
cairo_line_to (cr, x1, y);
cairo_stroke (cr);
}
for (i = 0; i < n_deaths; ++i)
{
double d = deaths[i];
double x = (d / N_YEARS) * WIDTH;
cairo_set_line_width (cr, DEATH_WIDTH);
cairo_move_to (cr, x, (0.5 - DEATH_HEIGHT / 2.0) * HEIGHT);
cairo_line_to (cr, x, (0.5 + DEATH_HEIGHT / 2.0) * HEIGHT);
cairo_set_source_rgb (cr, DEATH_COLOR);
cairo_stroke (cr);
}
in_cluster = 0;
for (i = 1; i < n_deaths; ++i)
{
double d0 = deaths[i - 1];
double d1 = deaths[i];
double x1 = (d1 / N_YEARS) * WIDTH;
if (!in_cluster && d1 - d0 <= 1.0 / DEATHS_PER_YEAR)
{
cluster_x0 = (d0 / N_YEARS) * WIDTH;
in_cluster = 1;
}
if (in_cluster && d1 - d0 > 1.0 / DEATHS_PER_YEAR)
{
double x1 = (d0 / N_YEARS) * WIDTH;
cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
cairo_move_to (cr, cluster_x0, y);
cairo_line_to (cr, x1, y);
cairo_set_line_width (cr, CLUSTER_WIDTH);
cairo_set_source_rgba (cr, CLUSTER_COLOR);
cairo_stroke (cr);
in_cluster = 0;
}
}
cairo_surface_write_to_png (surface, "diagram.png");
return 0;
}
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