1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
// Copyright 2015-2018 Hans Dembinski
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
//[ guide_histogram_projection
#include <boost/histogram.hpp>
#include <cassert>
#include <iostream>
#include <sstream>
int main() {
using namespace boost::histogram;
using namespace literals; // enables _c suffix
// make a 2d histogram
auto h = make_histogram(axis::regular<>(3, -1.0, 1.0), axis::integer<>(0, 2));
h(-0.9, 0);
h(0.9, 1);
h(0.1, 0);
auto hr0 = algorithm::project(h, 0_c); // keep only first axis
auto hr1 = algorithm::project(h, 1_c); // keep only second axis
// reduce does not remove counts; returned histograms are summed over
// the removed axes, so h, hr0, and hr1 have same number of total counts;
// we compute the sum of counts with the sum algorithm
assert(algorithm::sum(h) == 3 && algorithm::sum(hr0) == 3 && algorithm::sum(hr1) == 3);
std::ostringstream os1;
for (auto&& x : indexed(h))
os1 << "(" << x.index(0) << ", " << x.index(1) << "): " << *x << "\n";
std::cout << os1.str() << std::flush;
assert(os1.str() == "(0, 0): 1\n"
"(1, 0): 1\n"
"(2, 0): 0\n"
"(0, 1): 0\n"
"(1, 1): 0\n"
"(2, 1): 1\n");
std::ostringstream os2;
for (auto&& x : indexed(hr0)) os2 << "(" << x.index(0) << ", -): " << *x << "\n";
std::cout << os2.str() << std::flush;
assert(os2.str() == "(0, -): 1\n"
"(1, -): 1\n"
"(2, -): 1\n");
std::ostringstream os3;
for (auto&& x : indexed(hr1)) os3 << "(- ," << x.index(0) << "): " << *x << "\n";
std::cout << os3.str() << std::flush;
assert(os3.str() == "(- ,0): 2\n"
"(- ,1): 1\n");
}
//]
|
