53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
// Copyright 2019 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_custom_accumulators_3
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#include <boost/format.hpp>
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#include <boost/histogram.hpp>
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#include <iostream>
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#include <sstream>
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int main() {
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using namespace boost::histogram;
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// Accumulator accepts two samples and an optional weight and computes the mean of each.
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struct multi_mean {
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accumulators::mean<> mx, my;
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// called when no weight is passed
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void operator()(double x, double y) {
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mx(x);
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my(y);
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}
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// called when a weight is passed
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void operator()(weight_type<double> w, double x, double y) {
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mx(w, x);
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my(w, y);
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}
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};
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// Note: The implementation can be made more efficient by sharing the sum of weights.
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// Create a 1D histogram that uses the custom accumulator.
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auto h = make_histogram_with(dense_storage<multi_mean>(), axis::integer<>(0, 2));
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h(0, sample(1, 2)); // samples go to first cell
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h(0, sample(3, 4)); // samples go to first cell
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h(1, sample(5, 6), weight(2)); // samples go to second cell
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h(1, sample(7, 8), weight(3)); // samples go to second cell
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std::ostringstream os;
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for (auto&& bin : indexed(h)) {
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os << boost::format("index %i mean-x %.1f mean-y %.1f\n") % bin.index() %
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bin->mx.value() % bin->my.value();
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}
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std::cout << os.str() << std::flush;
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assert(os.str() == "index 0 mean-x 2.0 mean-y 3.0\n"
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"index 1 mean-x 6.2 mean-y 7.2\n");
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}
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//]
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