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1 | // Copyright 2018 Hans Dembinski |
2 | // | |
3 | // Distributed under the Boost Software License, Version 1.0. | |
4 | // (See accompanying file LICENSE_1_0.txt | |
5 | // or copy at http://www.boost.org/LICENSE_1_0.txt) | |
6 | ||
7 | #ifndef BOOST_HISTOGRAM_ALGORITHM_SUM_HPP | |
8 | #define BOOST_HISTOGRAM_ALGORITHM_SUM_HPP | |
9 | ||
10 | #include <boost/histogram/accumulators/sum.hpp> | |
11 | #include <boost/histogram/fwd.hpp> | |
f67539c2 | 12 | #include <boost/histogram/indexed.hpp> |
92f5a8d4 | 13 | #include <boost/mp11/utility.hpp> |
92f5a8d4 TL |
14 | #include <type_traits> |
15 | ||
16 | namespace boost { | |
17 | namespace histogram { | |
18 | namespace algorithm { | |
92f5a8d4 | 19 | |
f67539c2 | 20 | /** Compute the sum over all histogram cells (underflow/overflow included by default). |
92f5a8d4 | 21 | |
f67539c2 TL |
22 | The implementation favors accuracy and protection against overflow over speed. If the |
23 | value type of the histogram is an integral or floating point type, | |
24 | accumulators::sum<double> is used to compute the sum, else the original value type is | |
25 | used. Compilation fails, if the value type does not support operator+=. The return type | |
26 | is double if the value type of the histogram is integral or floating point, and the | |
27 | original value type otherwise. | |
28 | ||
29 | If you need a different trade-off, you can write your own loop or use `std::accumulate`: | |
30 | ``` | |
31 | // iterate over all bins | |
32 | auto sum_all = std::accumulate(hist.begin(), hist.end(), 0.0); | |
33 | ||
34 | // skip underflow/overflow bins | |
35 | double sum = 0; | |
36 | for (auto&& x : indexed(hist)) | |
37 | sum += *x; // dereference accessor | |
38 | ||
39 | // or: | |
40 | // auto ind = boost::histogram::indexed(hist); | |
41 | // auto sum = std::accumulate(ind.begin(), ind.end(), 0.0); | |
42 | ``` | |
43 | ||
44 | @returns accumulator type or double | |
45 | ||
46 | @param hist Const reference to the histogram. | |
47 | @param cov Iterate over all or only inner bins (optional, default: all). | |
48 | */ | |
92f5a8d4 | 49 | template <class A, class S> |
f67539c2 | 50 | auto sum(const histogram<A, S>& hist, const coverage cov = coverage::all) { |
92f5a8d4 | 51 | using T = typename histogram<A, S>::value_type; |
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52 | using sum_type = mp11::mp_if<std::is_arithmetic<T>, accumulators::sum<double>, T>; |
53 | sum_type sum; | |
54 | if (cov == coverage::all) | |
55 | for (auto&& x : hist) sum += x; | |
56 | else | |
57 | // sum += x also works if sum_type::operator+=(const sum_type&) exists | |
58 | for (auto&& x : indexed(hist)) sum += *x; | |
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59 | using R = mp11::mp_if<std::is_arithmetic<T>, double, T>; |
60 | return static_cast<R>(sum); | |
61 | } | |
f67539c2 | 62 | |
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63 | } // namespace algorithm |
64 | } // namespace histogram | |
65 | } // namespace boost | |
66 | ||
67 | #endif |