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 <iosfwd>
17 #include <numeric>
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
intervals()59 vector<result_type> intervals() const {return __b_;}
60 _LIBCPP_INLINE_VISIBILITY
densities()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
piecewise_linear_distribution()94 piecewise_linear_distribution() {}
95 template<class _InputIteratorB, class _InputIteratorW>
96 _LIBCPP_INLINE_VISIBILITY
piecewise_linear_distribution(_InputIteratorB __f_b,_InputIteratorB __l_b,_InputIteratorW __f_w)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
piecewise_linear_distribution(initializer_list<result_type> __bl,_UnaryOperation __fw)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
piecewise_linear_distribution(size_t __nw,result_type __xmin,result_type __xmax,_UnaryOperation __fw)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
piecewise_linear_distribution(const param_type & __p)117 explicit piecewise_linear_distribution(const param_type& __p)
118 : __p_(__p) {}
119
120 _LIBCPP_INLINE_VISIBILITY
reset()121 void reset() {}
122
123 // generating functions
124 template<class _URNG>
125 _LIBCPP_INLINE_VISIBILITY
operator()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
intervals()133 vector<result_type> intervals() const {return __p_.intervals();}
134 _LIBCPP_INLINE_VISIBILITY
densities()135 vector<result_type> densities() const {return __p_.densities();}
136
137 _LIBCPP_INLINE_VISIBILITY
param()138 param_type param() const {return __p_;}
139 _LIBCPP_INLINE_VISIBILITY
param(const param_type & __p)140 void param(const param_type& __p) {__p_ = __p;}
141
142 _LIBCPP_INLINE_VISIBILITY
min()143 result_type min() const {return __p_.__b_.front();}
144 _LIBCPP_INLINE_VISIBILITY
max()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
__init()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>
param_type()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>
param_type(_InputIteratorB __f_b,_InputIteratorB __l_b,_InputIteratorW __f_w)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>
param_type(initializer_list<result_type> __bl,_UnaryOperation __fw)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>
param_type(size_t __nw,result_type __xmin,result_type __xmax,_UnaryOperation __fw)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
operator()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
376