1 // Copyright 2019 Hans Dembinski
2 //
3 // Distributed under the Boost Software License, Version 1.0.
4 // (See accompanying file LICENSE_1_0.txt
5 // or copy at http://www.boost.org/LICENSE_1_0.txt)
6
7 //[ guide_fill_weighted_histogram
8
9 #include <boost/histogram.hpp>
10 #include <cassert>
11
main()12 int main() {
13 using namespace boost::histogram;
14
15 // Create a histogram with weight counters that keep track of a variance estimate.
16 auto h = make_weighted_histogram(axis::regular<>(3, 0.0, 1.0));
17
18 h(0.0, weight(1)); // weight 1 goes to first bin
19 h(0.1, weight(2)); // weight 2 goes to first bin
20 h(0.4, weight(3)); // weight 3 goes to second bin
21 h(0.5, weight(4)); // weight 4 goes to second bin
22
23 // chunk-wise filling is also supported
24 auto x = {0.2, 0.6};
25 auto w = {5, 6};
26 h.fill(x, weight(w));
27
28 // Weight counters have methods to access the value (sum of weights) and the variance
29 // (sum of weights squared, why this gives the variance is explained in the rationale)
30 assert(h[0].value() == 1 + 2 + 5);
31 assert(h[0].variance() == 1 * 1 + 2 * 2 + 5 * 5);
32 assert(h[1].value() == 3 + 4 + 6);
33 assert(h[1].variance() == 3 * 3 + 4 * 4 + 6 * 6);
34 }
35
36 //]
37