1 // Copyright 2015-2018 Hans Dembinski
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)
7 //[ guide_histogram_reduction
9 #include <boost/histogram.hpp>
13 using namespace boost::histogram;
15 // make a 2d histogram
16 auto h = make_histogram(axis::regular<>(4, 0.0, 4.0), axis::regular<>(4, -1.0, 1.0));
23 // shrink the first axis to remove the highest bin
24 // rebin the second axis by merging pairs of adjacent bins
25 auto h2 = algorithm::reduce(h, algorithm::shrink(0, 0.0, 3.0), algorithm::rebin(1, 2));
27 assert(h2.axis(0).size() == 3);
28 assert(h2.axis(0).bin(0).lower() == 0.0);
29 assert(h2.axis(0).bin(2).upper() == 3.0);
30 assert(h2.axis(1).size() == 2);
31 assert(h2.axis(1).bin(0).lower() == -1.0);
32 assert(h2.axis(1).bin(1).upper() == 1.0);
34 // reduce does not change the total count if the histogram has underflow/overflow bins;
35 // counts in removed bins are added to the corresponding under- and overflow bins
36 assert(algorithm::sum(h) == 4 && algorithm::sum(h2) == 4);