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_profile
8
9 #include <boost/format.hpp>
10 #include <boost/histogram.hpp>
11 #include <cassert>
12 #include <iostream>
13 #include <sstream>
14 #include <tuple>
15
main()16 int main() {
17 using namespace boost::histogram;
18
19 // make a profile, it computes the mean of the samples in each histogram cell
20 auto h = make_profile(axis::integer<>(0, 3));
21
22 // mean is computed from the values marked with the sample() helper function
23 h(0, sample(1)); // sample goes to cell 0
24 h(0, sample(2)); // sample goes to cell 0
25 h(1, sample(3)); // sample goes to cell 1
26 h(sample(4), 1); // sample goes to cell 1; sample can be first or last argument
27
28 // fills from tuples are also supported, 5 and 6 go to cell 2
29 auto a = std::make_tuple(2, sample(5));
30 auto b = std::make_tuple(sample(6), 2);
31 h(a);
32 h(b);
33
34 // builtin accumulators have methods to access their state
35 std::ostringstream os;
36 for (auto&& x : indexed(h)) {
37 // use `.` to access methods of accessor, like `index()`
38 // use `->` to access methods of accumulator
39 const auto i = x.index();
40 const auto n = x->count(); // how many samples are in this bin
41 const auto vl = x->value(); // mean value
42 const auto vr = x->variance(); // estimated variance of the mean value
43 os << boost::format("index %i count %i value %.1f variance %.1f\n") % i % n % vl % vr;
44 }
45
46 std::cout << os.str() << std::flush;
47
48 assert(os.str() == "index 0 count 2 value 1.5 variance 0.5\n"
49 "index 1 count 2 value 3.5 variance 0.5\n"
50 "index 2 count 2 value 5.5 variance 0.5\n");
51 }
52
53 //]
54