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9abbe46e3d
* Travis uses b2 and codecov now * replacing boost::multiprecision with custom implementation to avoid the dependency * improved axis implementation: `update` is now a normal method * introduced use_default tag type to set defaults * whitespace fixes and doc update
65 lines
2.5 KiB
C++
65 lines
2.5 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_fill_histogram
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#include <boost/histogram.hpp>
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#include <cassert>
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#include <functional>
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#include <numeric>
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#include <utility>
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#include <vector>
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int main() {
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using namespace boost::histogram;
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auto h = make_histogram(axis::integer<>(0, 3), axis::regular<>(2, 0.0, 1.0));
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// fill histogram, number of arguments must be equal to number of axes,
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// types must be convertible to axis value type (here double)
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h(0, 0.2); // increases bin counter by one
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h(2, 0.5, weight(2)); // increase bin counter by 2 instead of 1
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// fills from a tuple are also supported; passing a tuple of wrong size
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// causes an error at compile-time or an assertion at runtime in debug mode
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auto xy = std::make_tuple(1, 0.3);
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h(xy);
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// functional-style processing is also supported, generate some data...
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std::vector<std::tuple<int, double>> input_data;
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input_data.emplace_back(0, 0.8);
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input_data.emplace_back(2, 0.4);
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input_data.emplace_back(5, 0.7); // goes into overflow bin of first axis
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// std::for_each takes the functor by value, a reference wrapper avoid copies
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std::for_each(input_data.begin(), input_data.end(), std::ref(h));
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// once histogram is filled, access cells using operator[] or at(...)
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// - operator[] can only accept a single argument in the current version of C++,
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// it is convenient when you have a 1D histogram
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// - at(...) can accept several values, so use this by default
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// - underflow bins are at index -1, overflow bins at index `size()`
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// - passing an invalid index triggers a std::out_of_range exception
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assert(h.at(0, 0) == 1);
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assert(h.at(0, 1) == 1);
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assert(h.at(1, 0) == 1);
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assert(h.at(1, 1) == 0);
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assert(h.at(2, 0) == 1);
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assert(h.at(2, 1) == 2);
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assert(h.at(-1, -1) == 0); // underflow for axis 0 and 1
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assert(h.at(-1, 0) == 0); // underflow for axis 0, normal bin for axis 1
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assert(h.at(-1, 2) == 0); // underflow for axis 0, overflow for axis 1
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assert(h.at(3, 1) == 1); // overflow for axis 0, normal bin for axis 1
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// iteration over values works, but see next example for a better way
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// - iteration using begin() and end() includes under- and overflow bins
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// - iteration order is an implementation detail and may change in future versions
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const double sum = std::accumulate(h.begin(), h.end(), 0.0);
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assert(sum == 7);
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}
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//]
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