libcxx/include/__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___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H
  10 #define _LIBCPP___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H
  11
  12 #include <__algorithm/upper_bound.h>
  13 #include <__config>
  14 #include <__random/is_valid.h>
  15 #include <__random/uniform_real_distribution.h>
  16 #include <cmath>
  17 #include <iosfwd>
  18 #include <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 <__undef_macros>
  26
  27 _LIBCPP_BEGIN_NAMESPACE_STD
  28
  29 template<class _RealType = double>
  30 class _LIBCPP_TEMPLATE_VIS piecewise_linear_distribution
  31 {
  32 public:
  33     // types
  34     typedef _RealType result_type;
  35
  36     class _LIBCPP_TEMPLATE_VIS param_type
  37     {
  38         vector<result_type> __b_;
  39         vector<result_type> __densities_;
  40         vector<result_type> __areas_;
  41     public:
  42         typedef piecewise_linear_distribution distribution_type;
  43
  44         _LIBCPP_HIDE_FROM_ABI param_type();
  45         template<class _InputIteratorB, class _InputIteratorW>
  46         _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b,
  47                        _InputIteratorW __f_w);
  48 #ifndef _LIBCPP_CXX03_LANG
  49         template<class _UnaryOperation>
  50         _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);
  51 #endif // _LIBCPP_CXX03_LANG
  52         template<class _UnaryOperation>
  53         _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax,
  54                        _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_INLINE_VISIBILITY
  59         vector<result_type> intervals() const {return __b_;}
  60         _LIBCPP_INLINE_VISIBILITY
  61         vector<result_type> densities() const {return __densities_;}
  62
  63         friend _LIBCPP_INLINE_VISIBILITY
  64             bool operator==(const param_type& __x, const param_type& __y)
  65             {return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;}
  66         friend _LIBCPP_INLINE_VISIBILITY
  67             bool operator!=(const param_type& __x, const param_type& __y)
  68             {return !(__x == __y);}
  69
  70     private:
  71         _LIBCPP_HIDE_FROM_ABI void __init();
  72
  73         friend class piecewise_linear_distribution;
  74
  75         template <class _CharT, class _Traits, class _RT>
  76         friend
  77         basic_ostream<_CharT, _Traits>&
  78         operator<<(basic_ostream<_CharT, _Traits>& __os,
  79                    const piecewise_linear_distribution<_RT>& __x);
  80
  81         template <class _CharT, class _Traits, class _RT>
  82         friend
  83         basic_istream<_CharT, _Traits>&
  84         operator>>(basic_istream<_CharT, _Traits>& __is,
  85                    piecewise_linear_distribution<_RT>& __x);
  86     };
  87
  88 private:
  89     param_type __p_;
  90
  91 public:
  92     // constructor and reset functions
  93     _LIBCPP_INLINE_VISIBILITY
  94     piecewise_linear_distribution() {}
  95     template<class _InputIteratorB, class _InputIteratorW>
  96         _LIBCPP_INLINE_VISIBILITY
  97         piecewise_linear_distribution(_InputIteratorB __f_b,
  98                                       _InputIteratorB __l_b,
  99                                       _InputIteratorW __f_w)
 100         : __p_(__f_b, __l_b, __f_w) {}
 101
 102 #ifndef _LIBCPP_CXX03_LANG
 103     template<class _UnaryOperation>
 104         _LIBCPP_INLINE_VISIBILITY
 105         piecewise_linear_distribution(initializer_list<result_type> __bl,
 106                                       _UnaryOperation __fw)
 107         : __p_(__bl, __fw) {}
 108 #endif // _LIBCPP_CXX03_LANG
 109
 110     template<class _UnaryOperation>
 111         _LIBCPP_INLINE_VISIBILITY
 112         piecewise_linear_distribution(size_t __nw, result_type __xmin,
 113                                       result_type __xmax, _UnaryOperation __fw)
 114         : __p_(__nw, __xmin, __xmax, __fw) {}
 115
 116     _LIBCPP_INLINE_VISIBILITY
 117     explicit piecewise_linear_distribution(const param_type& __p)
 118         : __p_(__p) {}
 119
 120     _LIBCPP_INLINE_VISIBILITY
 121     void reset() {}
 122
 123     // generating functions
 124     template<class _URNG>
 125         _LIBCPP_INLINE_VISIBILITY
 126         result_type operator()(_URNG& __g)
 127         {return (*this)(__g, __p_);}
 128     template<class _URNG>
 129     _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
 130
 131     // property functions
 132     _LIBCPP_INLINE_VISIBILITY
 133     vector<result_type> intervals() const {return __p_.intervals();}
 134     _LIBCPP_INLINE_VISIBILITY
 135     vector<result_type> densities() const {return __p_.densities();}
 136
 137     _LIBCPP_INLINE_VISIBILITY
 138     param_type param() const {return __p_;}
 139     _LIBCPP_INLINE_VISIBILITY
 140     void param(const param_type& __p) {__p_ = __p;}
 141
 142     _LIBCPP_INLINE_VISIBILITY
 143     result_type min() const {return __p_.__b_.front();}
 144     _LIBCPP_INLINE_VISIBILITY
 145     result_type max() const {return __p_.__b_.back();}
 146
 147     friend _LIBCPP_INLINE_VISIBILITY
 148         bool operator==(const piecewise_linear_distribution& __x,
 149                         const piecewise_linear_distribution& __y)
 150         {return __x.__p_ == __y.__p_;}
 151     friend _LIBCPP_INLINE_VISIBILITY
 152         bool operator!=(const piecewise_linear_distribution& __x,
 153                         const piecewise_linear_distribution& __y)
 154         {return !(__x == __y);}
 155
 156     template <class _CharT, class _Traits, class _RT>
 157     friend
 158     basic_ostream<_CharT, _Traits>&
 159     operator<<(basic_ostream<_CharT, _Traits>& __os,
 160                const piecewise_linear_distribution<_RT>& __x);
 161
 162     template <class _CharT, class _Traits, class _RT>
 163     friend
 164     basic_istream<_CharT, _Traits>&
 165     operator>>(basic_istream<_CharT, _Traits>& __is,
 166                piecewise_linear_distribution<_RT>& __x);
 167 };
 168
 169 template<class _RealType>
 170 typename piecewise_linear_distribution<_RealType>::param_type &
 171 piecewise_linear_distribution<_RealType>::param_type::operator=
 172                                                        (const param_type& __rhs)
 173 {
 174 //  These can throw
 175     __b_.reserve        (__rhs.__b_.size ());
 176     __densities_.reserve(__rhs.__densities_.size());
 177     __areas_.reserve    (__rhs.__areas_.size());
 178
 179 //  These can not throw
 180     __b_         = __rhs.__b_;
 181     __densities_ = __rhs.__densities_;
 182     __areas_     =  __rhs.__areas_;
 183     return *this;
 184 }
 185
 186
 187 template<class _RealType>
 188 void
 189 piecewise_linear_distribution<_RealType>::param_type::__init()
 190 {
 191     __areas_.assign(__densities_.size() - 1, result_type());
 192     result_type __sp = 0;
 193     for (size_t __i = 0; __i < __areas_.size(); ++__i)
 194     {
 195         __areas_[__i] = (__densities_[__i+1] + __densities_[__i]) *
 196                         (__b_[__i+1] - __b_[__i]) * .5;
 197         __sp += __areas_[__i];
 198     }
 199     for (size_t __i = __areas_.size(); __i > 1;)
 200     {
 201         --__i;
 202         __areas_[__i] = __areas_[__i-1] / __sp;
 203     }
 204     __areas_[0] = 0;
 205     for (size_t __i = 1; __i < __areas_.size(); ++__i)
 206         __areas_[__i] += __areas_[__i-1];
 207     for (size_t __i = 0; __i < __densities_.size(); ++__i)
 208         __densities_[__i] /= __sp;
 209 }
 210
 211 template<class _RealType>
 212 piecewise_linear_distribution<_RealType>::param_type::param_type()
 213     : __b_(2),
 214       __densities_(2, 1.0),
 215       __areas_(1, 0.0)
 216 {
 217     __b_[1] = 1;
 218 }
 219
 220 template<class _RealType>
 221 template<class _InputIteratorB, class _InputIteratorW>
 222 piecewise_linear_distribution<_RealType>::param_type::param_type(
 223         _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
 224     : __b_(__f_b, __l_b)
 225 {
 226     if (__b_.size() < 2)
 227     {
 228         __b_.resize(2);
 229         __b_[0] = 0;
 230         __b_[1] = 1;
 231         __densities_.assign(2, 1.0);
 232         __areas_.assign(1, 0.0);
 233     }
 234     else
 235     {
 236         __densities_.reserve(__b_.size());
 237         for (size_t __i = 0; __i < __b_.size(); ++__i, ++__f_w)
 238             __densities_.push_back(*__f_w);
 239         __init();
 240     }
 241 }
 242
 243 #ifndef _LIBCPP_CXX03_LANG
 244
 245 template<class _RealType>
 246 template<class _UnaryOperation>
 247 piecewise_linear_distribution<_RealType>::param_type::param_type(
 248         initializer_list<result_type> __bl, _UnaryOperation __fw)
 249     : __b_(__bl.begin(), __bl.end())
 250 {
 251     if (__b_.size() < 2)
 252     {
 253         __b_.resize(2);
 254         __b_[0] = 0;
 255         __b_[1] = 1;
 256         __densities_.assign(2, 1.0);
 257         __areas_.assign(1, 0.0);
 258     }
 259     else
 260     {
 261         __densities_.reserve(__b_.size());
 262         for (size_t __i = 0; __i < __b_.size(); ++__i)
 263             __densities_.push_back(__fw(__b_[__i]));
 264         __init();
 265     }
 266 }
 267
 268 #endif // _LIBCPP_CXX03_LANG
 269
 270 template<class _RealType>
 271 template<class _UnaryOperation>
 272 piecewise_linear_distribution<_RealType>::param_type::param_type(
 273         size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
 274     : __b_(__nw == 0 ? 2 : __nw + 1)
 275 {
 276     size_t __n = __b_.size() - 1;
 277     result_type __d = (__xmax - __xmin) / __n;
 278     __densities_.reserve(__b_.size());
 279     for (size_t __i = 0; __i < __n; ++__i)
 280     {
 281         __b_[__i] = __xmin + __i * __d;
 282         __densities_.push_back(__fw(__b_[__i]));
 283     }
 284     __b_[__n] = __xmax;
 285     __densities_.push_back(__fw(__b_[__n]));
 286     __init();
 287 }
 288
 289 template<class _RealType>
 290 template<class _URNG>
 291 _RealType
 292 piecewise_linear_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
 293 {
 294     static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
 295     typedef uniform_real_distribution<result_type> _Gen;
 296     result_type __u = _Gen()(__g);
 297     ptrdiff_t __k = _VSTD::upper_bound(__p.__areas_.begin(), __p.__areas_.end(),
 298                                       __u) - __p.__areas_.begin() - 1;
 299     __u -= __p.__areas_[__k];
 300     const result_type __dk = __p.__densities_[__k];
 301     const result_type __dk1 = __p.__densities_[__k+1];
 302     const result_type __deltad = __dk1 - __dk;
 303     const result_type __bk = __p.__b_[__k];
 304     if (__deltad == 0)
 305         return __u / __dk + __bk;
 306     const result_type __bk1 = __p.__b_[__k+1];
 307     const result_type __deltab = __bk1 - __bk;
 308     return (__bk * __dk1 - __bk1 * __dk +
 309         _VSTD::sqrt(__deltab * (__deltab * __dk * __dk + 2 * __deltad * __u))) /
 310         __deltad;
 311 }
 312
 313 template <class _CharT, class _Traits, class _RT>
 314 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 315 operator<<(basic_ostream<_CharT, _Traits>& __os,
 316            const piecewise_linear_distribution<_RT>& __x)
 317 {
 318     __save_flags<_CharT, _Traits> __lx(__os);
 319     typedef basic_ostream<_CharT, _Traits> _OStream;
 320     __os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
 321                _OStream::scientific);
 322     _CharT __sp = __os.widen(' ');
 323     __os.fill(__sp);
 324     size_t __n = __x.__p_.__b_.size();
 325     __os << __n;
 326     for (size_t __i = 0; __i < __n; ++__i)
 327         __os << __sp << __x.__p_.__b_[__i];
 328     __n = __x.__p_.__densities_.size();
 329     __os << __sp << __n;
 330     for (size_t __i = 0; __i < __n; ++__i)
 331         __os << __sp << __x.__p_.__densities_[__i];
 332     __n = __x.__p_.__areas_.size();
 333     __os << __sp << __n;
 334     for (size_t __i = 0; __i < __n; ++__i)
 335         __os << __sp << __x.__p_.__areas_[__i];
 336     return __os;
 337 }
 338
 339 template <class _CharT, class _Traits, class _RT>
 340 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 341 operator>>(basic_istream<_CharT, _Traits>& __is,
 342            piecewise_linear_distribution<_RT>& __x)
 343 {
 344     typedef piecewise_linear_distribution<_RT> _Eng;
 345     typedef typename _Eng::result_type result_type;
 346     __save_flags<_CharT, _Traits> __lx(__is);
 347     typedef basic_istream<_CharT, _Traits> _Istream;
 348     __is.flags(_Istream::dec | _Istream::skipws);
 349     size_t __n;
 350     __is >> __n;
 351     vector<result_type> __b(__n);
 352     for (size_t __i = 0; __i < __n; ++__i)
 353         __is >> __b[__i];
 354     __is >> __n;
 355     vector<result_type> __densities(__n);
 356     for (size_t __i = 0; __i < __n; ++__i)
 357         __is >> __densities[__i];
 358     __is >> __n;
 359     vector<result_type> __areas(__n);
 360     for (size_t __i = 0; __i < __n; ++__i)
 361         __is >> __areas[__i];
 362     if (!__is.fail())
 363     {
 364         swap(__x.__p_.__b_, __b);
 365         swap(__x.__p_.__densities_, __densities);
 366         swap(__x.__p_.__areas_, __areas);
 367     }
 368     return __is;
 369 }
 370
 371 _LIBCPP_END_NAMESPACE_STD
 372
 373 _LIBCPP_POP_MACROS
 374
 375 #endif // _LIBCPP___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H