40 lines
1.2 KiB
C++
40 lines
1.2 KiB
C++
// Copyright 2015-2018 Hans Dembinski
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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//[ guide_histogram_reduction
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#include <boost/histogram.hpp>
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#include <cassert>
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int main() {
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using namespace boost::histogram;
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// make a 2d histogram
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auto h = make_histogram(axis::regular<>(4, 0.0, 4.0), axis::regular<>(4, -1.0, 1.0));
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h(0, -0.9);
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h(1, 0.9);
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h(2, 0.1);
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h(3, 0.1);
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// shrink the first axis to remove the highest bin
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// rebin the second axis by merging pairs of adjacent bins
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auto h2 = algorithm::reduce(h, algorithm::shrink(0, 0.0, 3.0), algorithm::rebin(1, 2));
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assert(h2.axis(0).size() == 3);
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assert(h2.axis(0).bin(0).lower() == 0.0);
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assert(h2.axis(0).bin(2).upper() == 3.0);
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assert(h2.axis(1).size() == 2);
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assert(h2.axis(1).bin(0).lower() == -1.0);
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assert(h2.axis(1).bin(1).upper() == 1.0);
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// reduce does not change the total count if the histogram has underflow/overflow bins;
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// counts in removed bins are added to the corresponding under- and overflow bins
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assert(algorithm::sum(h) == 4 && algorithm::sum(h2) == 4);
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}
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//]
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