libcxx/include/__cxx03/__random/piecewise_linear_distribution.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___CXX03___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H
  10 #define _LIBCPP___CXX03___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H
  11
  12 #include <__cxx03/__algorithm/upper_bound.h>
  13 #include <__cxx03/__config>
  14 #include <__cxx03/__random/is_valid.h>
  15 #include <__cxx03/__random/uniform_real_distribution.h>
  16 #include <__cxx03/cmath>
  17 #include <__cxx03/iosfwd>
  18 #include <__cxx03/vector>
  19
  20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  21 #  pragma GCC system_header
  22 #endif
  23
  24 _LIBCPP_PUSH_MACROS
  25 #include <__cxx03/__undef_macros>
  26
  27 _LIBCPP_BEGIN_NAMESPACE_STD
  28
  29 template <class _RealType = double>
  30 class _LIBCPP_TEMPLATE_VIS piecewise_linear_distribution {
  31   static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
  32                 "RealType must be a supported floating-point type");
  33
  34 public:
  35   // types
  36   typedef _RealType result_type;
  37
  38   class _LIBCPP_TEMPLATE_VIS param_type {
  39     vector<result_type> __b_;
  40     vector<result_type> __densities_;
  41     vector<result_type> __areas_;
  42
  43   public:
  44     typedef piecewise_linear_distribution distribution_type;
  45
  46     _LIBCPP_HIDE_FROM_ABI param_type();
  47     template <class _InputIteratorB, class _InputIteratorW>
  48     _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);
  49 #ifndef _LIBCPP_CXX03_LANG
  50     template <class _UnaryOperation>
  51     _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);
  52 #endif // _LIBCPP_CXX03_LANG
  53     template <class _UnaryOperation>
  54     _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);
  55     _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;
  56     _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);
  57
  58     _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }
  59     _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }
  60
  61     friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
  62       return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;
  63     }
  64     friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
  65
  66   private:
  67     _LIBCPP_HIDE_FROM_ABI void __init();
  68
  69     friend class piecewise_linear_distribution;
  70
  71     template <class _CharT, class _Traits, class _RT>
  72     friend basic_ostream<_CharT, _Traits>&
  73     operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);
  74
  75     template <class _CharT, class _Traits, class _RT>
  76     friend basic_istream<_CharT, _Traits>&
  77     operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);
  78   };
  79
  80 private:
  81   param_type __p_;
  82
  83 public:
  84   // constructor and reset functions
  85   _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution() {}
  86   template <class _InputIteratorB, class _InputIteratorW>
  87   _LIBCPP_HIDE_FROM_ABI
  88   piecewise_linear_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
  89       : __p_(__f_b, __l_b, __f_w) {}
  90
  91 #ifndef _LIBCPP_CXX03_LANG
  92   template <class _UnaryOperation>
  93   _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution(initializer_list<result_type> __bl, _UnaryOperation __fw)
  94       : __p_(__bl, __fw) {}
  95 #endif // _LIBCPP_CXX03_LANG
  96
  97   template <class _UnaryOperation>
  98   _LIBCPP_HIDE_FROM_ABI
  99   piecewise_linear_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
 100       : __p_(__nw, __xmin, __xmax, __fw) {}
 101
 102   _LIBCPP_HIDE_FROM_ABI explicit piecewise_linear_distribution(const param_type& __p) : __p_(__p) {}
 103
 104   _LIBCPP_HIDE_FROM_ABI void reset() {}
 105
 106   // generating functions
 107   template <class _URNG>
 108   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
 109     return (*this)(__g, __p_);
 110   }
 111   template <class _URNG>
 112   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
 113
 114   // property functions
 115   _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }
 116   _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }
 117
 118   _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
 119   _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
 120
 121   _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }
 122   _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }
 123
 124   friend _LIBCPP_HIDE_FROM_ABI bool
 125   operator==(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {
 126     return __x.__p_ == __y.__p_;
 127   }
 128   friend _LIBCPP_HIDE_FROM_ABI bool
 129   operator!=(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {
 130     return !(__x == __y);
 131   }
 132
 133   template <class _CharT, class _Traits, class _RT>
 134   friend basic_ostream<_CharT, _Traits>&
 135   operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);
 136
 137   template <class _CharT, class _Traits, class _RT>
 138   friend basic_istream<_CharT, _Traits>&
 139   operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);
 140 };
 141
 142 template <class _RealType>
 143 typename piecewise_linear_distribution<_RealType>::param_type&
 144 piecewise_linear_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {
 145   //  These can throw
 146   __b_.reserve(__rhs.__b_.size());
 147   __densities_.reserve(__rhs.__densities_.size());
 148   __areas_.reserve(__rhs.__areas_.size());
 149
 150   //  These can not throw
 151   __b_         = __rhs.__b_;
 152   __densities_ = __rhs.__densities_;
 153   __areas_     = __rhs.__areas_;
 154   return *this;
 155 }
 156
 157 template <class _RealType>
 158 void piecewise_linear_distribution<_RealType>::param_type::__init() {
 159   __areas_.assign(__densities_.size() - 1, result_type());
 160   result_type __sp = 0;
 161   for (size_t __i = 0; __i < __areas_.size(); ++__i) {
 162     __areas_[__i] = (__densities_[__i + 1] + __densities_[__i]) * (__b_[__i + 1] - __b_[__i]) * .5;
 163     __sp += __areas_[__i];
 164   }
 165   for (size_t __i = __areas_.size(); __i > 1;) {
 166     --__i;
 167     __areas_[__i] = __areas_[__i - 1] / __sp;
 168   }
 169   __areas_[0] = 0;
 170   for (size_t __i = 1; __i < __areas_.size(); ++__i)
 171     __areas_[__i] += __areas_[__i - 1];
 172   for (size_t __i = 0; __i < __densities_.size(); ++__i)
 173     __densities_[__i] /= __sp;
 174 }
 175
 176 template <class _RealType>
 177 piecewise_linear_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(2, 1.0), __areas_(1, 0.0) {
 178   __b_[1] = 1;
 179 }
 180
 181 template <class _RealType>
 182 template <class _InputIteratorB, class _InputIteratorW>
 183 piecewise_linear_distribution<_RealType>::param_type::param_type(
 184     _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
 185     : __b_(__f_b, __l_b) {
 186   if (__b_.size() < 2) {
 187     __b_.resize(2);
 188     __b_[0] = 0;
 189     __b_[1] = 1;
 190     __densities_.assign(2, 1.0);
 191     __areas_.assign(1, 0.0);
 192   } else {
 193     __densities_.reserve(__b_.size());
 194     for (size_t __i = 0; __i < __b_.size(); ++__i, ++__f_w)
 195       __densities_.push_back(*__f_w);
 196     __init();
 197   }
 198 }
 199
 200 #ifndef _LIBCPP_CXX03_LANG
 201
 202 template <class _RealType>
 203 template <class _UnaryOperation>
 204 piecewise_linear_distribution<_RealType>::param_type::param_type(
 205     initializer_list<result_type> __bl, _UnaryOperation __fw)
 206     : __b_(__bl.begin(), __bl.end()) {
 207   if (__b_.size() < 2) {
 208     __b_.resize(2);
 209     __b_[0] = 0;
 210     __b_[1] = 1;
 211     __densities_.assign(2, 1.0);
 212     __areas_.assign(1, 0.0);
 213   } else {
 214     __densities_.reserve(__b_.size());
 215     for (size_t __i = 0; __i < __b_.size(); ++__i)
 216       __densities_.push_back(__fw(__b_[__i]));
 217     __init();
 218   }
 219 }
 220
 221 #endif // _LIBCPP_CXX03_LANG
 222
 223 template <class _RealType>
 224 template <class _UnaryOperation>
 225 piecewise_linear_distribution<_RealType>::param_type::param_type(
 226     size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
 227     : __b_(__nw == 0 ? 2 : __nw + 1) {
 228   size_t __n      = __b_.size() - 1;
 229   result_type __d = (__xmax - __xmin) / __n;
 230   __densities_.reserve(__b_.size());
 231   for (size_t __i = 0; __i < __n; ++__i) {
 232     __b_[__i] = __xmin + __i * __d;
 233     __densities_.push_back(__fw(__b_[__i]));
 234   }
 235   __b_[__n] = __xmax;
 236   __densities_.push_back(__fw(__b_[__n]));
 237   __init();
 238 }
 239
 240 template <class _RealType>
 241 template <class _URNG>
 242 _RealType piecewise_linear_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
 243   static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
 244   typedef uniform_real_distribution<result_type> _Gen;
 245   result_type __u = _Gen()(__g);
 246   ptrdiff_t __k   = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;
 247   __u -= __p.__areas_[__k];
 248   const result_type __dk     = __p.__densities_[__k];
 249   const result_type __dk1    = __p.__densities_[__k + 1];
 250   const result_type __deltad = __dk1 - __dk;
 251   const result_type __bk     = __p.__b_[__k];
 252   if (__deltad == 0)
 253     return __u / __dk + __bk;
 254   const result_type __bk1    = __p.__b_[__k + 1];
 255   const result_type __deltab = __bk1 - __bk;
 256   return (__bk * __dk1 - __bk1 * __dk + std::sqrt(__deltab * (__deltab * __dk * __dk + 2 * __deltad * __u))) / __deltad;
 257 }
 258
 259 template <class _CharT, class _Traits, class _RT>
 260 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 261 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x) {
 262   __save_flags<_CharT, _Traits> __lx(__os);
 263   typedef basic_ostream<_CharT, _Traits> _OStream;
 264   __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
 265   _CharT __sp = __os.widen(' ');
 266   __os.fill(__sp);
 267   size_t __n = __x.__p_.__b_.size();
 268   __os << __n;
 269   for (size_t __i = 0; __i < __n; ++__i)
 270     __os << __sp << __x.__p_.__b_[__i];
 271   __n = __x.__p_.__densities_.size();
 272   __os << __sp << __n;
 273   for (size_t __i = 0; __i < __n; ++__i)
 274     __os << __sp << __x.__p_.__densities_[__i];
 275   __n = __x.__p_.__areas_.size();
 276   __os << __sp << __n;
 277   for (size_t __i = 0; __i < __n; ++__i)
 278     __os << __sp << __x.__p_.__areas_[__i];
 279   return __os;
 280 }
 281
 282 template <class _CharT, class _Traits, class _RT>
 283 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 284 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x) {
 285   typedef piecewise_linear_distribution<_RT> _Eng;
 286   typedef typename _Eng::result_type result_type;
 287   __save_flags<_CharT, _Traits> __lx(__is);
 288   typedef basic_istream<_CharT, _Traits> _Istream;
 289   __is.flags(_Istream::dec | _Istream::skipws);
 290   size_t __n;
 291   __is >> __n;
 292   vector<result_type> __b(__n);
 293   for (size_t __i = 0; __i < __n; ++__i)
 294     __is >> __b[__i];
 295   __is >> __n;
 296   vector<result_type> __densities(__n);
 297   for (size_t __i = 0; __i < __n; ++__i)
 298     __is >> __densities[__i];
 299   __is >> __n;
 300   vector<result_type> __areas(__n);
 301   for (size_t __i = 0; __i < __n; ++__i)
 302     __is >> __areas[__i];
 303   if (!__is.fail()) {
 304     swap(__x.__p_.__b_, __b);
 305     swap(__x.__p_.__densities_, __densities);
 306     swap(__x.__p_.__areas_, __areas);
 307   }
 308   return __is;
 309 }
 310
 311 _LIBCPP_END_NAMESPACE_STD
 312
 313 _LIBCPP_POP_MACROS
 314
 315 #endif // _LIBCPP___CXX03___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H