//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H
#define _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H
#include <__algorithm/upper_bound.h>
#include <__config>
#include <__random/is_valid.h>
#include <__random/uniform_real_distribution.h>
#include <iosfwd>
#include <numeric>
#include <vector>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _RealType = double>
class _LIBCPP_TEMPLATE_VIS piecewise_constant_distribution {
static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
"RealType must be a supported floating-point type");
public:
// types
typedef _RealType result_type;
class _LIBCPP_TEMPLATE_VIS param_type {
vector<result_type> __b_;
vector<result_type> __densities_;
vector<result_type> __areas_;
public:
typedef piecewise_constant_distribution distribution_type;
_LIBCPP_HIDE_FROM_ABI param_type();
template <class _InputIteratorB, class _InputIteratorW>
_LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);
#ifndef _LIBCPP_CXX03_LANG
template <class _UnaryOperation>
_LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);
#endif // _LIBCPP_CXX03_LANG
template <class _UnaryOperation>
_LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);
_LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;
_LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);
_LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }
_LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }
friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;
}
friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
private:
_LIBCPP_HIDE_FROM_ABI void __init();
friend class piecewise_constant_distribution;
template <class _CharT, class _Traits, class _RT>
friend basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);
template <class _CharT, class _Traits, class _RT>
friend basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);
};
private:
param_type __p_;
public:
// constructor and reset functions
_LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution() {}
template <class _InputIteratorB, class _InputIteratorW>
_LIBCPP_HIDE_FROM_ABI
piecewise_constant_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
: __p_(__f_b, __l_b, __f_w) {}
#ifndef _LIBCPP_CXX03_LANG
template <class _UnaryOperation>
_LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution(initializer_list<result_type> __bl, _UnaryOperation __fw)
: __p_(__bl, __fw) {}
#endif // _LIBCPP_CXX03_LANG
template <class _UnaryOperation>
_LIBCPP_HIDE_FROM_ABI
piecewise_constant_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
: __p_(__nw, __xmin, __xmax, __fw) {}
_LIBCPP_HIDE_FROM_ABI explicit piecewise_constant_distribution(const param_type& __p) : __p_(__p) {}
_LIBCPP_HIDE_FROM_ABI void reset() {}
// generating functions
template <class _URNG>
_LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
return (*this)(__g, __p_);
}
template <class _URNG>
_LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
// property functions
_LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }
_LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }
_LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
_LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
_LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }
_LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }
friend _LIBCPP_HIDE_FROM_ABI bool
operator==(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {
return __x.__p_ == __y.__p_;
}
friend _LIBCPP_HIDE_FROM_ABI bool
operator!=(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {
return !(__x == __y);
}
template <class _CharT, class _Traits, class _RT>
friend basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);
template <class _CharT, class _Traits, class _RT>
friend basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);
};
template <class _RealType>
typename piecewise_constant_distribution<_RealType>::param_type&
piecewise_constant_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {
// These can throw
__b_.reserve(__rhs.__b_.size());
__densities_.reserve(__rhs.__densities_.size());
__areas_.reserve(__rhs.__areas_.size());
// These can not throw
__b_ = __rhs.__b_;
__densities_ = __rhs.__densities_;
__areas_ = __rhs.__areas_;
return *this;
}
template <class _RealType>
void piecewise_constant_distribution<_RealType>::param_type::__init() {
// __densities_ contains non-normalized areas
result_type __total_area = std::accumulate(__densities_.begin(), __densities_.end(), result_type());
for (size_t __i = 0; __i < __densities_.size(); ++__i)
__densities_[__i] /= __total_area;
// __densities_ contains normalized areas
__areas_.assign(__densities_.size(), result_type());
std::partial_sum(__densities_.begin(), __densities_.end() - 1, __areas_.begin() + 1);
// __areas_ contains partial sums of normalized areas: [0, __densities_ - 1]
__densities_.back() = 1 - __areas_.back(); // correct round off error
for (size_t __i = 0; __i < __densities_.size(); ++__i)
__densities_[__i] /= (__b_[__i + 1] - __b_[__i]);
// __densities_ now contains __densities_
}
template <class _RealType>
piecewise_constant_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(1, 1.0), __areas_(1, 0.0) {
__b_[1] = 1;
}
template <class _RealType>
template <class _InputIteratorB, class _InputIteratorW>
piecewise_constant_distribution<_RealType>::param_type::param_type(
_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
: __b_(__f_b, __l_b) {
if (__b_.size() < 2) {
__b_.resize(2);
__b_[0] = 0;
__b_[1] = 1;
__densities_.assign(1, 1.0);
__areas_.assign(1, 0.0);
} else {
__densities_.reserve(__b_.size() - 1);
for (size_t __i = 0; __i < __b_.size() - 1; ++__i, ++__f_w)
__densities_.push_back(*__f_w);
__init();
}
}
#ifndef _LIBCPP_CXX03_LANG
template <class _RealType>
template <class _UnaryOperation>
piecewise_constant_distribution<_RealType>::param_type::param_type(
initializer_list<result_type> __bl, _UnaryOperation __fw)
: __b_(__bl.begin(), __bl.end()) {
if (__b_.size() < 2) {
__b_.resize(2);
__b_[0] = 0;
__b_[1] = 1;
__densities_.assign(1, 1.0);
__areas_.assign(1, 0.0);
} else {
__densities_.reserve(__b_.size() - 1);
for (size_t __i = 0; __i < __b_.size() - 1; ++__i)
__densities_.push_back(__fw((__b_[__i + 1] + __b_[__i]) * .5));
__init();
}
}
#endif // _LIBCPP_CXX03_LANG
template <class _RealType>
template <class _UnaryOperation>
piecewise_constant_distribution<_RealType>::param_type::param_type(
size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
: __b_(__nw == 0 ? 2 : __nw + 1) {
size_t __n = __b_.size() - 1;
result_type __d = (__xmax - __xmin) / __n;
__densities_.reserve(__n);
for (size_t __i = 0; __i < __n; ++__i) {
__b_[__i] = __xmin + __i * __d;
__densities_.push_back(__fw(__b_[__i] + __d * .5));
}
__b_[__n] = __xmax;
__init();
}
template <class _RealType>
template <class _URNG>
_RealType piecewise_constant_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
typedef uniform_real_distribution<result_type> _Gen;
result_type __u = _Gen()(__g);
ptrdiff_t __k = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;
return (__u - __p.__areas_[__k]) / __p.__densities_[__k] + __p.__b_[__k];
}
template <class _CharT, class _Traits, class _RT>
_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x) {
__save_flags<_CharT, _Traits> __lx(__os);
typedef basic_ostream<_CharT, _Traits> _OStream;
__os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
_CharT __sp = __os.widen(' ');
__os.fill(__sp);
size_t __n = __x.__p_.__b_.size();
__os << __n;
for (size_t __i = 0; __i < __n; ++__i)
__os << __sp << __x.__p_.__b_[__i];
__n = __x.__p_.__densities_.size();
__os << __sp << __n;
for (size_t __i = 0; __i < __n; ++__i)
__os << __sp << __x.__p_.__densities_[__i];
__n = __x.__p_.__areas_.size();
__os << __sp << __n;
for (size_t __i = 0; __i < __n; ++__i)
__os << __sp << __x.__p_.__areas_[__i];
return __os;
}
template <class _CharT, class _Traits, class _RT>
_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x) {
typedef piecewise_constant_distribution<_RT> _Eng;
typedef typename _Eng::result_type result_type;
__save_flags<_CharT, _Traits> __lx(__is);
typedef basic_istream<_CharT, _Traits> _Istream;
__is.flags(_Istream::dec | _Istream::skipws);
size_t __n;
__is >> __n;
vector<result_type> __b(__n);
for (size_t __i = 0; __i < __n; ++__i)
__is >> __b[__i];
__is >> __n;
vector<result_type> __densities(__n);
for (size_t __i = 0; __i < __n; ++__i)
__is >> __densities[__i];
__is >> __n;
vector<result_type> __areas(__n);
for (size_t __i = 0; __i < __n; ++__i)
__is >> __areas[__i];
if (!__is.fail()) {
swap(__x.__p_.__b_, __b);
swap(__x.__p_.__densities_, __densities);
swap(__x.__p_.__areas_, __areas);
}
return __is;
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H
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