223 lines
6.7 KiB
C++
223 lines
6.7 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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#ifndef BOOST_HISTOGRAM_ALGORITHM_REDUCE_HPP
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#define BOOST_HISTOGRAM_ALGORITHM_REDUCE_HPP
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#include <boost/assert.hpp>
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#include <boost/histogram/detail/axes.hpp>
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#include <boost/histogram/detail/meta.hpp>
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#include <boost/histogram/fwd.hpp>
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#include <boost/histogram/indexed.hpp>
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#include <boost/histogram/unsafe_access.hpp>
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#include <boost/throw_exception.hpp>
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#include <cmath>
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#include <limits>
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#include <stdexcept>
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#include <type_traits>
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namespace boost {
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namespace histogram {
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namespace algorithm {
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/**
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Option type returned by the helper functions shrink_and_rebin(), shrink(), rebin().
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*/
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struct reduce_option {
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#ifndef BOOST_HISTOGRAM_DOXYGEN_INVOKED
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unsigned iaxis = 0;
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double lower, upper;
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unsigned merge = 0;
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reduce_option() noexcept = default;
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reduce_option(unsigned i, double l, double u, unsigned m)
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: iaxis(i), lower(l), upper(u), merge(m) {
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if (lower == upper)
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BOOST_THROW_EXCEPTION(std::invalid_argument("lower != upper required"));
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if (merge == 0) BOOST_THROW_EXCEPTION(std::invalid_argument("merge > 0 required"));
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}
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#endif
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};
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/**
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Shrink and rebin option.
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@param iaxis which axis to operate on.
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@param lower lowest bound that should be kept.
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@param upper highest bound that should be kept. If upper is inside bin interval, the
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whole interval is removed.
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@param merge how many adjacent bins to merge into one.
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*/
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inline auto shrink_and_rebin(unsigned iaxis, double lower, double upper, unsigned merge) {
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return reduce_option{iaxis, lower, upper, merge};
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}
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/**
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Shrink option.
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@param iaxis which axis to operate on.
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@param lower lowest bound that should be kept.
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@param upper highest bound that should be kept. If upper is inside bin interval, the
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whole interval is removed.
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*/
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inline auto shrink(unsigned iaxis, double lower, double upper) {
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return reduce_option{iaxis, lower, upper, 1};
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}
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/**
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Rebin option.
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@param iaxis which axis to operate on.
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@param merge how many adjacent bins to merge into one.
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*/
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inline auto rebin(unsigned iaxis, unsigned merge) {
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return reduce_option{iaxis, std::numeric_limits<double>::quiet_NaN(),
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std::numeric_limits<double>::quiet_NaN(), merge};
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}
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/**
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Convenience overload for single axis.
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@param lower lowest bound that should be kept.
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@param upper highest bound that should be kept. If upper is inside bin interval, the
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whole interval is removed.
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@param merge how many adjacent bins to merge into one.
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*/
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inline auto shrink_and_rebin(double lower, double upper, unsigned merge) {
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return shrink_and_rebin(0, lower, upper, merge);
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}
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/**
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Convenience overload for single axis.
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@param lower lowest bound that should be kept.
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@param upper highest bound that should be kept. If upper is inside bin interval, the
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whole interval is removed.
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*/
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inline auto shrink(double lower, double upper) { return shrink(0, lower, upper); }
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/**
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Convenience overload for single axis.
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@param merge how many adjacent bins to merge into one.
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*/
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inline auto rebin(unsigned merge) { return rebin(0, merge); }
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/**
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Shrink and/or rebin axes of a histogram.
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Returns the reduced copy of the histogram.
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@param hist original histogram.
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@param options iterable sequence of reduce_options, generated by shrink_and_rebin(),
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shrink(), and rebin().
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*/
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#ifndef BOOST_HISTOGRAM_DOXYGEN_INVOKED
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template <class Histogram, class Iterable, class = detail::requires_iterable<Iterable>>
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#else
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template <class Histogram, class Iterable>
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#endif
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decltype(auto) reduce(const Histogram& hist, const Iterable& options) {
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const auto& old_axes = unsafe_access::axes(hist);
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struct option_item : reduce_option {
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int begin, end;
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};
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auto opts = detail::make_stack_buffer<option_item>(old_axes);
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for (const auto& o : options) {
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auto& oi = opts[o.iaxis];
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if (oi.merge > 0) // did we already set the option for this axis?
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BOOST_THROW_EXCEPTION(std::invalid_argument("indices must be unique"));
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oi.lower = o.lower;
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oi.upper = o.upper;
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oi.merge = o.merge;
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}
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// make new axes container with default-constructed axis instances
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auto axes = detail::make_default(old_axes);
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detail::static_if<detail::is_tuple<decltype(axes)>>(
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[](auto&, const auto&) {},
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[](auto& axes, const auto& old_axes) {
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axes.reserve(old_axes.size());
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for (const auto& a : old_axes) axes.emplace_back(detail::make_default(a));
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},
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axes, old_axes);
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// override default-constructed axis instances with modified instances
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unsigned iaxis = 0;
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hist.for_each_axis([&](const auto& a) {
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using T = detail::remove_cvref_t<decltype(a)>;
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auto& o = opts[iaxis];
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o.begin = 0;
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o.end = a.size();
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if (o.merge > 0) { // option is set?
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if (o.lower < o.upper) {
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while (o.begin != o.end && a.value(o.begin) < o.lower) ++o.begin;
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while (o.end != o.begin && a.value(o.end - 1) >= o.upper) --o.end;
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} else if (o.lower > o.upper) {
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// for inverted axis::regular
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while (o.begin != o.end && a.value(o.begin) > o.lower) ++o.begin;
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while (o.end != o.begin && a.value(o.end - 1) <= o.upper) --o.end;
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}
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o.end -= (o.end - o.begin) % o.merge;
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auto a2 = T(a, o.begin, o.end, o.merge);
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axis::get<T>(detail::axis_get(axes, iaxis)) = a2;
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} else {
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o.merge = 1;
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axis::get<T>(detail::axis_get(axes, iaxis)) = a;
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}
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++iaxis;
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});
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auto storage = detail::make_default(unsafe_access::storage(hist));
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auto result = Histogram(std::move(axes), std::move(storage));
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auto idx = detail::make_stack_buffer<int>(unsafe_access::axes(result));
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for (auto x : indexed(hist, coverage::all)) {
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auto i = idx.begin();
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auto o = opts.begin();
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for (auto j : x.indices()) {
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*i = (j - o->begin);
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if (*i <= -1)
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*i = -1;
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else {
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*i /= o->merge;
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const int end = (o->end - o->begin) / o->merge;
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if (*i > end) *i = end;
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}
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++i;
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++o;
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}
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result.at(idx) += *x;
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}
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return result;
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}
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/**
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Shrink and/or rebin axes of a histogram.
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Returns the modified copy.
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@param hist original histogram.
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@param opt reduce option generated by shrink_and_rebin(), shrink(), and rebin().
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@param opts more reduce_options.
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*/
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template <class Histogram, class... Ts>
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decltype(auto) reduce(const Histogram& hist, const reduce_option& opt, Ts&&... opts) {
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// this must be in one line, because any of the ts could be a temporary
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return reduce(hist, std::initializer_list<reduce_option>{opt, opts...});
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}
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} // namespace algorithm
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} // namespace histogram
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} // namespace boost
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#endif
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