// 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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#ifndef BOOST_HISTOGRAM_AXIS_REGULAR_HPP
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#define BOOST_HISTOGRAM_AXIS_REGULAR_HPP
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#include <boost/core/nvp.hpp>
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#include <boost/histogram/axis/interval_view.hpp>
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#include <boost/histogram/axis/iterator.hpp>
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#include <boost/histogram/axis/metadata_base.hpp>
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#include <boost/histogram/axis/option.hpp>
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#include <boost/histogram/detail/convert_integer.hpp>
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#include <boost/histogram/detail/relaxed_equal.hpp>
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#include <boost/histogram/detail/replace_type.hpp>
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#include <boost/histogram/fwd.hpp>
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#include <boost/mp11/utility.hpp>
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#include <boost/throw_exception.hpp>
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#include <cassert>
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#include <cmath>
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#include <limits>
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#include <stdexcept>
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#include <string>
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#include <type_traits>
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#include <utility>
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namespace boost {
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namespace histogram {
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namespace detail {
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template <class T>
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using get_scale_type_helper = typename T::value_type;
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template <class T>
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using get_scale_type = mp11::mp_eval_or<T, detail::get_scale_type_helper, T>;
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struct one_unit {};
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template <class T>
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T operator*(T&& t, const one_unit&) {
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return std::forward<T>(t);
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}
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template <class T>
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T operator/(T&& t, const one_unit&) {
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return std::forward<T>(t);
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}
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template <class T>
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using get_unit_type_helper = typename T::unit_type;
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template <class T>
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using get_unit_type = mp11::mp_eval_or<one_unit, detail::get_unit_type_helper, T>;
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template <class T, class R = get_scale_type<T>>
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R get_scale(const T& t) {
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return t / get_unit_type<T>();
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}
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} // namespace detail
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namespace axis {
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namespace transform {
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/// Identity transform for equidistant bins.
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struct id {
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/// Pass-through.
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template <class T>
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static T forward(T&& x) noexcept {
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return std::forward<T>(x);
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}
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/// Pass-through.
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template <class T>
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static T inverse(T&& x) noexcept {
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return std::forward<T>(x);
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}
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template <class Archive>
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void serialize(Archive&, unsigned /* version */) {}
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};
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/// Log transform for equidistant bins in log-space.
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struct log {
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/// Returns log(x) of external value x.
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template <class T>
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static T forward(T x) {
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return std::log(x);
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}
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/// Returns exp(x) for internal value x.
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template <class T>
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static T inverse(T x) {
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return std::exp(x);
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}
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template <class Archive>
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void serialize(Archive&, unsigned /* version */) {}
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};
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/// Sqrt transform for equidistant bins in sqrt-space.
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struct sqrt {
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/// Returns sqrt(x) of external value x.
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template <class T>
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static T forward(T x) {
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return std::sqrt(x);
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}
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/// Returns x^2 of internal value x.
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template <class T>
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static T inverse(T x) {
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return x * x;
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}
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template <class Archive>
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void serialize(Archive&, unsigned /* version */) {}
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};
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/// Pow transform for equidistant bins in pow-space.
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struct pow {
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double power = 1; /**< power index */
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/// Make transform with index p.
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explicit pow(double p) : power(p) {}
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pow() = default;
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/// Returns pow(x, power) of external value x.
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template <class T>
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auto forward(T x) const {
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return std::pow(x, power);
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}
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/// Returns pow(x, 1/power) of external value x.
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template <class T>
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auto inverse(T x) const {
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return std::pow(x, 1.0 / power);
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}
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bool operator==(const pow& o) const noexcept { return power == o.power; }
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template <class Archive>
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void serialize(Archive& ar, unsigned /* version */) {
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ar& make_nvp("power", power);
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}
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};
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} // namespace transform
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#ifndef BOOST_HISTOGRAM_DOXYGEN_INVOKED
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// Type envelope to mark value as step size
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template <class T>
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struct step_type {
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T value;
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};
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#endif
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/**
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Helper function to mark argument as step size.
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*/
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template <class T>
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step_type<T> step(T t) {
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return step_type<T>{t};
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}
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/**
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Axis for equidistant intervals on the real line.
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The most common binning strategy. Very fast. Binning is a O(1) operation.
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@tparam Value input value type, must be floating point.
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@tparam Transform builtin or user-defined transform type.
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@tparam MetaData type to store meta data.
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@tparam Options see boost::histogram::axis::option (all values allowed).
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*/
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template <class Value, class Transform, class MetaData, class Options>
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class regular : public iterator_mixin<regular<Value, Transform, MetaData, Options>>,
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protected detail::replace_default<Transform, transform::id>,
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public metadata_base_t<MetaData> {
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// these must be private, so that they are not automatically inherited
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using value_type = Value;
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using transform_type = detail::replace_default<Transform, transform::id>;
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using metadata_base = metadata_base_t<MetaData>;
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using metadata_type = typename metadata_base::metadata_type;
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using options_type =
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detail::replace_default<Options, decltype(option::underflow | option::overflow)>;
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static_assert(std::is_nothrow_move_constructible<transform_type>::value,
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"transform must be no-throw move constructible");
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static_assert(std::is_nothrow_move_assignable<transform_type>::value,
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"transform must be no-throw move assignable");
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using unit_type = detail::get_unit_type<value_type>;
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using internal_value_type = detail::get_scale_type<value_type>;
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static_assert(std::is_floating_point<internal_value_type>::value,
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"regular axis requires floating point type");
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static_assert(
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(!options_type::test(option::circular) && !options_type::test(option::growth)) ||
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(options_type::test(option::circular) ^ options_type::test(option::growth)),
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"circular and growth options are mutually exclusive");
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public:
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constexpr regular() = default;
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/** Construct n bins over real transformed range [start, stop).
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*
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* @param trans transform instance to use.
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* @param n number of bins.
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* @param start low edge of first bin.
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* @param stop high edge of last bin.
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* @param meta description of the axis (optional).
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*/
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regular(transform_type trans, unsigned n, value_type start, value_type stop,
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metadata_type meta = {})
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: transform_type(std::move(trans))
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, metadata_base(std::move(meta))
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, size_(static_cast<index_type>(n))
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, min_(this->forward(detail::get_scale(start)))
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, delta_(this->forward(detail::get_scale(stop)) - min_) {
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if (size() == 0) BOOST_THROW_EXCEPTION(std::invalid_argument("bins > 0 required"));
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if (!std::isfinite(min_) || !std::isfinite(delta_))
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BOOST_THROW_EXCEPTION(
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std::invalid_argument("forward transform of start or stop invalid"));
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if (delta_ == 0)
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BOOST_THROW_EXCEPTION(std::invalid_argument("range of axis is zero"));
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}
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/** Construct n bins over real range [start, stop).
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*
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* @param n number of bins.
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* @param start low edge of first bin.
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* @param stop high edge of last bin.
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* @param meta description of the axis (optional).
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*/
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regular(unsigned n, value_type start, value_type stop, metadata_type meta = {})
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: regular({}, n, start, stop, std::move(meta)) {}
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/** Construct bins with the given step size over real transformed range
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* [start, stop).
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*
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* @param trans transform instance to use.
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* @param step width of a single bin.
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* @param start low edge of first bin.
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* @param stop upper limit of high edge of last bin (see below).
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* @param meta description of the axis (optional).
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*
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* The axis computes the number of bins as n = abs(stop - start) / step,
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* rounded down. This means that stop is an upper limit to the actual value
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* (start + n * step).
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*/
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template <class T>
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regular(transform_type trans, step_type<T> step, value_type start, value_type stop,
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metadata_type meta = {})
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: regular(trans, static_cast<index_type>(std::abs(stop - start) / step.value),
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start,
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start + static_cast<index_type>(std::abs(stop - start) / step.value) *
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step.value,
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std::move(meta)) {}
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/** Construct bins with the given step size over real range [start, stop).
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*
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* @param step width of a single bin.
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* @param start low edge of first bin.
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* @param stop upper limit of high edge of last bin (see below).
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* @param meta description of the axis (optional).
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*
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* The axis computes the number of bins as n = abs(stop - start) / step,
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* rounded down. This means that stop is an upper limit to the actual value
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* (start + n * step).
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*/
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template <class T>
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regular(step_type<T> step, value_type start, value_type stop, metadata_type meta = {})
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: regular({}, step, start, stop, std::move(meta)) {}
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/// Constructor used by algorithm::reduce to shrink and rebin (not for users).
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regular(const regular& src, index_type begin, index_type end, unsigned merge)
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: regular(src.transform(), (end - begin) / merge, src.value(begin), src.value(end),
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src.metadata()) {
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assert((end - begin) % merge == 0);
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if (options_type::test(option::circular) && !(begin == 0 && end == src.size()))
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BOOST_THROW_EXCEPTION(std::invalid_argument("cannot shrink circular axis"));
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}
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/// Return instance of the transform type.
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const transform_type& transform() const noexcept { return *this; }
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/// Return index for value argument.
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index_type index(value_type x) const noexcept {
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// Runs in hot loop, please measure impact of changes
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auto z = (this->forward(x / unit_type{}) - min_) / delta_;
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if (options_type::test(option::circular)) {
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if (std::isfinite(z)) {
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z -= std::floor(z);
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return static_cast<index_type>(z * size());
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}
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} else {
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if (z < 1) {
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if (z >= 0)
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return static_cast<index_type>(z * size());
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else
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return -1;
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}
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}
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return size(); // also returned if x is NaN
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}
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/// Returns index and shift (if axis has grown) for the passed argument.
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std::pair<index_type, index_type> update(value_type x) noexcept {
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assert(options_type::test(option::growth));
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const auto z = (this->forward(x / unit_type{}) - min_) / delta_;
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if (z < 1) { // don't use i here!
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if (z >= 0) {
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const auto i = static_cast<axis::index_type>(z * size());
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return {i, 0};
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}
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if (z != -std::numeric_limits<internal_value_type>::infinity()) {
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const auto stop = min_ + delta_;
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const auto i = static_cast<axis::index_type>(std::floor(z * size()));
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min_ += i * (delta_ / size());
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delta_ = stop - min_;
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size_ -= i;
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return {0, -i};
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}
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// z is -infinity
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return {-1, 0};
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}
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// z either beyond range, infinite, or NaN
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if (z < std::numeric_limits<internal_value_type>::infinity()) {
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const auto i = static_cast<axis::index_type>(z * size());
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const auto n = i - size() + 1;
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delta_ /= size();
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delta_ *= size() + n;
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size_ += n;
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return {i, -n};
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}
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// z either infinite or NaN
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return {size(), 0};
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}
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/// Return value for fractional index argument.
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value_type value(real_index_type i) const noexcept {
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auto z = i / size();
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if (!options_type::test(option::circular) && z < 0.0)
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z = -std::numeric_limits<internal_value_type>::infinity() * delta_;
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else if (options_type::test(option::circular) || z <= 1.0)
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z = (1.0 - z) * min_ + z * (min_ + delta_);
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else {
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z = std::numeric_limits<internal_value_type>::infinity() * delta_;
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}
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return static_cast<value_type>(this->inverse(z) * unit_type());
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}
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/// Return bin for index argument.
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decltype(auto) bin(index_type idx) const noexcept {
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return interval_view<regular>(*this, idx);
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}
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/// Returns the number of bins, without over- or underflow.
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index_type size() const noexcept { return size_; }
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/// Returns the options.
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static constexpr unsigned options() noexcept { return options_type::value; }
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template <class V, class T, class M, class O>
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bool operator==(const regular<V, T, M, O>& o) const noexcept {
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return detail::relaxed_equal{}(transform(), o.transform()) && size() == o.size() &&
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min_ == o.min_ && delta_ == o.delta_ &&
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detail::relaxed_equal{}(this->metadata(), o.metadata());
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}
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template <class V, class T, class M, class O>
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bool operator!=(const regular<V, T, M, O>& o) const noexcept {
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return !operator==(o);
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}
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template <class Archive>
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void serialize(Archive& ar, unsigned /* version */) {
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ar& make_nvp("transform", static_cast<transform_type&>(*this));
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ar& make_nvp("size", size_);
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ar& make_nvp("meta", this->metadata());
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ar& make_nvp("min", min_);
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ar& make_nvp("delta", delta_);
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}
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private:
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index_type size_{0};
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internal_value_type min_{0}, delta_{1};
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template <class V, class T, class M, class O>
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friend class regular;
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};
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#if __cpp_deduction_guides >= 201606
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template <class T>
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regular(unsigned, T, T)
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->regular<detail::convert_integer<T, double>, transform::id, null_type>;
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template <class T, class M>
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regular(unsigned, T, T, M)
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->regular<detail::convert_integer<T, double>, transform::id,
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detail::replace_cstring<std::decay_t<M>>>;
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template <class Tr, class T, class = detail::requires_transform<Tr, T>>
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regular(Tr, unsigned, T, T)->regular<detail::convert_integer<T, double>, Tr, null_type>;
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template <class Tr, class T, class M>
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regular(Tr, unsigned, T, T, M)
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->regular<detail::convert_integer<T, double>, Tr,
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detail::replace_cstring<std::decay_t<M>>>;
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#endif
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/// Regular axis with circular option already set.
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template <class Value = double, class MetaData = use_default, class Options = use_default>
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#ifndef BOOST_HISTOGRAM_DOXYGEN_INVOKED
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using circular = regular<Value, transform::id, MetaData,
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decltype(detail::replace_default<Options, option::overflow_t>{} |
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option::circular)>;
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#else
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class circular;
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#endif
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} // namespace axis
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} // namespace histogram
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} // namespace boost
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#endif
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