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- // 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_reduction
- #include <boost/histogram.hpp>
- #include <cassert>
- int main() {
- using namespace boost::histogram;
- // make a 2d histogram
- auto h = make_histogram(axis::regular<>(4, 0.0, 4.0), axis::regular<>(4, -1.0, 1.0));
- h(0, -0.9);
- h(1, 0.9);
- h(2, 0.1);
- h(3, 0.1);
- // shrink the first axis to remove the highest bin
- // rebin the second axis by merging pairs of adjacent bins
- auto h2 = algorithm::reduce(h, algorithm::shrink(0, 0.0, 3.0), algorithm::rebin(1, 2));
- assert(h2.axis(0).size() == 3);
- assert(h2.axis(0).bin(0).lower() == 0.0);
- assert(h2.axis(0).bin(2).upper() == 3.0);
- assert(h2.axis(1).size() == 2);
- assert(h2.axis(1).bin(0).lower() == -1.0);
- assert(h2.axis(1).bin(1).upper() == 1.0);
- // reduce does not change the total count if the histogram has underflow/overflow bins;
- // counts in removed bins are added to the corresponding under- and overflow bins
- assert(algorithm::sum(h) == 4 && algorithm::sum(h2) == 4);
- }
- //]
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