v1/__random/piecewise_constant_distribution.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H
0010 #define _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H
0011
0012 #include <__algorithm/upper_bound.h>
0013 #include <__config>
0014 #include <__cstddef/ptrdiff_t.h>
0015 #include <__random/is_valid.h>
0016 #include <__random/uniform_real_distribution.h>
0017 #include <__vector/vector.h>
0018 #include <initializer_list>
0019 #include <iosfwd>
0020 #include <numeric>
0021
0022 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0023 #  pragma GCC system_header
0024 #endif
0025
0026 _LIBCPP_PUSH_MACROS
0027 #include <__undef_macros>
0028
0029 _LIBCPP_BEGIN_NAMESPACE_STD
0030
0031 template <class _RealType = double>
0032 class _LIBCPP_TEMPLATE_VIS piecewise_constant_distribution {
0033   static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
0034                 "RealType must be a supported floating-point type");
0035
0036 public:
0037   // types
0038   typedef _RealType result_type;
0039
0040   class _LIBCPP_TEMPLATE_VIS param_type {
0041     vector<result_type> __b_;
0042     vector<result_type> __densities_;
0043     vector<result_type> __areas_;
0044
0045   public:
0046     typedef piecewise_constant_distribution distribution_type;
0047
0048     _LIBCPP_HIDE_FROM_ABI param_type();
0049     template <class _InputIteratorB, class _InputIteratorW>
0050     _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);
0051 #ifndef _LIBCPP_CXX03_LANG
0052     template <class _UnaryOperation>
0053     _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);
0054 #endif // _LIBCPP_CXX03_LANG
0055     template <class _UnaryOperation>
0056     _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);
0057     _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;
0058     _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);
0059
0060     _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }
0061     _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }
0062
0063     friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
0064       return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;
0065     }
0066     friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
0067
0068   private:
0069     _LIBCPP_HIDE_FROM_ABI void __init();
0070
0071     friend class piecewise_constant_distribution;
0072
0073     template <class _CharT, class _Traits, class _RT>
0074     friend basic_ostream<_CharT, _Traits>&
0075     operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);
0076
0077     template <class _CharT, class _Traits, class _RT>
0078     friend basic_istream<_CharT, _Traits>&
0079     operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);
0080   };
0081
0082 private:
0083   param_type __p_;
0084
0085 public:
0086   // constructor and reset functions
0087   _LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution() {}
0088   template <class _InputIteratorB, class _InputIteratorW>
0089   _LIBCPP_HIDE_FROM_ABI
0090   piecewise_constant_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
0091       : __p_(__f_b, __l_b, __f_w) {}
0092
0093 #ifndef _LIBCPP_CXX03_LANG
0094   template <class _UnaryOperation>
0095   _LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution(initializer_list<result_type> __bl, _UnaryOperation __fw)
0096       : __p_(__bl, __fw) {}
0097 #endif // _LIBCPP_CXX03_LANG
0098
0099   template <class _UnaryOperation>
0100   _LIBCPP_HIDE_FROM_ABI
0101   piecewise_constant_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
0102       : __p_(__nw, __xmin, __xmax, __fw) {}
0103
0104   _LIBCPP_HIDE_FROM_ABI explicit piecewise_constant_distribution(const param_type& __p) : __p_(__p) {}
0105
0106   _LIBCPP_HIDE_FROM_ABI void reset() {}
0107
0108   // generating functions
0109   template <class _URNG>
0110   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
0111     return (*this)(__g, __p_);
0112   }
0113   template <class _URNG>
0114   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
0115
0116   // property functions
0117   _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }
0118   _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }
0119
0120   _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
0121   _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
0122
0123   _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }
0124   _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }
0125
0126   friend _LIBCPP_HIDE_FROM_ABI bool
0127   operator==(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {
0128     return __x.__p_ == __y.__p_;
0129   }
0130   friend _LIBCPP_HIDE_FROM_ABI bool
0131   operator!=(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {
0132     return !(__x == __y);
0133   }
0134
0135   template <class _CharT, class _Traits, class _RT>
0136   friend basic_ostream<_CharT, _Traits>&
0137   operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);
0138
0139   template <class _CharT, class _Traits, class _RT>
0140   friend basic_istream<_CharT, _Traits>&
0141   operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);
0142 };
0143
0144 template <class _RealType>
0145 typename piecewise_constant_distribution<_RealType>::param_type&
0146 piecewise_constant_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {
0147   //  These can throw
0148   __b_.reserve(__rhs.__b_.size());
0149   __densities_.reserve(__rhs.__densities_.size());
0150   __areas_.reserve(__rhs.__areas_.size());
0151
0152   //  These can not throw
0153   __b_         = __rhs.__b_;
0154   __densities_ = __rhs.__densities_;
0155   __areas_     = __rhs.__areas_;
0156   return *this;
0157 }
0158
0159 template <class _RealType>
0160 void piecewise_constant_distribution<_RealType>::param_type::__init() {
0161   // __densities_ contains non-normalized areas
0162   result_type __total_area = std::accumulate(__densities_.begin(), __densities_.end(), result_type());
0163   for (size_t __i = 0; __i < __densities_.size(); ++__i)
0164     __densities_[__i] /= __total_area;
0165   // __densities_ contains normalized areas
0166   __areas_.assign(__densities_.size(), result_type());
0167   std::partial_sum(__densities_.begin(), __densities_.end() - 1, __areas_.begin() + 1);
0168   // __areas_ contains partial sums of normalized areas: [0, __densities_ - 1]
0169   __densities_.back() = 1 - __areas_.back(); // correct round off error
0170   for (size_t __i = 0; __i < __densities_.size(); ++__i)
0171     __densities_[__i] /= (__b_[__i + 1] - __b_[__i]);
0172   // __densities_ now contains __densities_
0173 }
0174
0175 template <class _RealType>
0176 piecewise_constant_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(1, 1.0), __areas_(1, 0.0) {
0177   __b_[1] = 1;
0178 }
0179
0180 template <class _RealType>
0181 template <class _InputIteratorB, class _InputIteratorW>
0182 piecewise_constant_distribution<_RealType>::param_type::param_type(
0183     _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
0184     : __b_(__f_b, __l_b) {
0185   if (__b_.size() < 2) {
0186     __b_.resize(2);
0187     __b_[0] = 0;
0188     __b_[1] = 1;
0189     __densities_.assign(1, 1.0);
0190     __areas_.assign(1, 0.0);
0191   } else {
0192     __densities_.reserve(__b_.size() - 1);
0193     for (size_t __i = 0; __i < __b_.size() - 1; ++__i, ++__f_w)
0194       __densities_.push_back(*__f_w);
0195     __init();
0196   }
0197 }
0198
0199 #ifndef _LIBCPP_CXX03_LANG
0200
0201 template <class _RealType>
0202 template <class _UnaryOperation>
0203 piecewise_constant_distribution<_RealType>::param_type::param_type(
0204     initializer_list<result_type> __bl, _UnaryOperation __fw)
0205     : __b_(__bl.begin(), __bl.end()) {
0206   if (__b_.size() < 2) {
0207     __b_.resize(2);
0208     __b_[0] = 0;
0209     __b_[1] = 1;
0210     __densities_.assign(1, 1.0);
0211     __areas_.assign(1, 0.0);
0212   } else {
0213     __densities_.reserve(__b_.size() - 1);
0214     for (size_t __i = 0; __i < __b_.size() - 1; ++__i)
0215       __densities_.push_back(__fw((__b_[__i + 1] + __b_[__i]) * .5));
0216     __init();
0217   }
0218 }
0219
0220 #endif // _LIBCPP_CXX03_LANG
0221
0222 template <class _RealType>
0223 template <class _UnaryOperation>
0224 piecewise_constant_distribution<_RealType>::param_type::param_type(
0225     size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
0226     : __b_(__nw == 0 ? 2 : __nw + 1) {
0227   size_t __n      = __b_.size() - 1;
0228   result_type __d = (__xmax - __xmin) / __n;
0229   __densities_.reserve(__n);
0230   for (size_t __i = 0; __i < __n; ++__i) {
0231     __b_[__i] = __xmin + __i * __d;
0232     __densities_.push_back(__fw(__b_[__i] + __d * .5));
0233   }
0234   __b_[__n] = __xmax;
0235   __init();
0236 }
0237
0238 template <class _RealType>
0239 template <class _URNG>
0240 _RealType piecewise_constant_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
0241   static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
0242   typedef uniform_real_distribution<result_type> _Gen;
0243   result_type __u = _Gen()(__g);
0244   ptrdiff_t __k   = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;
0245   return (__u - __p.__areas_[__k]) / __p.__densities_[__k] + __p.__b_[__k];
0246 }
0247
0248 template <class _CharT, class _Traits, class _RT>
0249 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
0250 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x) {
0251   __save_flags<_CharT, _Traits> __lx(__os);
0252   typedef basic_ostream<_CharT, _Traits> _OStream;
0253   __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
0254   _CharT __sp = __os.widen(' ');
0255   __os.fill(__sp);
0256   size_t __n = __x.__p_.__b_.size();
0257   __os << __n;
0258   for (size_t __i = 0; __i < __n; ++__i)
0259     __os << __sp << __x.__p_.__b_[__i];
0260   __n = __x.__p_.__densities_.size();
0261   __os << __sp << __n;
0262   for (size_t __i = 0; __i < __n; ++__i)
0263     __os << __sp << __x.__p_.__densities_[__i];
0264   __n = __x.__p_.__areas_.size();
0265   __os << __sp << __n;
0266   for (size_t __i = 0; __i < __n; ++__i)
0267     __os << __sp << __x.__p_.__areas_[__i];
0268   return __os;
0269 }
0270
0271 template <class _CharT, class _Traits, class _RT>
0272 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
0273 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x) {
0274   typedef piecewise_constant_distribution<_RT> _Eng;
0275   typedef typename _Eng::result_type result_type;
0276   __save_flags<_CharT, _Traits> __lx(__is);
0277   typedef basic_istream<_CharT, _Traits> _Istream;
0278   __is.flags(_Istream::dec | _Istream::skipws);
0279   size_t __n;
0280   __is >> __n;
0281   vector<result_type> __b(__n);
0282   for (size_t __i = 0; __i < __n; ++__i)
0283     __is >> __b[__i];
0284   __is >> __n;
0285   vector<result_type> __densities(__n);
0286   for (size_t __i = 0; __i < __n; ++__i)
0287     __is >> __densities[__i];
0288   __is >> __n;
0289   vector<result_type> __areas(__n);
0290   for (size_t __i = 0; __i < __n; ++__i)
0291     __is >> __areas[__i];
0292   if (!__is.fail()) {
0293     swap(__x.__p_.__b_, __b);
0294     swap(__x.__p_.__densities_, __densities);
0295     swap(__x.__p_.__areas_, __areas);
0296   }
0297   return __is;
0298 }
0299
0300 _LIBCPP_END_NAMESPACE_STD
0301
0302 _LIBCPP_POP_MACROS
0303
0304 #endif // _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H