57 lines
1.5 KiB
C++
57 lines
1.5 KiB
C++
// Copyright 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_custom_2d_axis
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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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// axis which returns 1 if the input falls inside the unit circle and zero otherwise
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struct circle_axis {
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// accepts a 2D point in form of a std::tuple
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axis::index_type index(const std::tuple<double, double>& point) const {
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const auto x = std::get<0>(point);
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const auto y = std::get<1>(point);
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return x * x + y * y <= 1.0;
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}
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axis::index_type size() const { return 2; }
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};
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auto h1 = make_histogram(circle_axis());
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// fill looks normal for a histogram which has only one Nd-axis
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h1(0, 0); // in
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h1(0, -1); // in
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h1(0, 1); // in
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h1(-1, 0); // in
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h1(1, 0); // in
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h1(1, 1); // out
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h1(-1, -1); // out
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// 2D histogram, but only 1D index
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assert(h1.at(0) == 2); // out
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assert(h1.at(1) == 5); // in
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// other axes can be combined with a Nd-axis
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auto h2 = make_histogram(circle_axis(), axis::category<std::string>({"red", "blue"}));
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// now we need to pass arguments for Nd-axis explicitly as std::tuple
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h2(std::make_tuple(0, 0), "red");
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h2(std::make_tuple(1, 1), "blue");
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// 3D histogram, but only 2D index
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assert(h2.at(0, 0) == 0); // out, red
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assert(h2.at(0, 1) == 1); // out, blue
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assert(h2.at(1, 0) == 1); // in, red
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assert(h2.at(1, 1) == 0); // in, blue
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}
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//]
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