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 param_type();
45 template<class _InputIteratorB, class _InputIteratorW>
46 param_type(_InputIteratorB __f_b, _InputIteratorB __l_b,
47 _InputIteratorW __f_w);
48 #ifndef _LIBCPP_CXX03_LANG
49 template<class _UnaryOperation>
50 param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);
51 #endif // _LIBCPP_CXX03_LANG
52 template<class _UnaryOperation>
53 param_type(size_t __nw, result_type __xmin, result_type __xmax,
54 _UnaryOperation __fw);
55 param_type(param_type const&) = default;
56 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 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> result_type operator()(_URNG& __g, const param_type& __p);
129
130 // property functions
131 _LIBCPP_INLINE_VISIBILITY
intervals()132 vector<result_type> intervals() const {return __p_.intervals();}
133 _LIBCPP_INLINE_VISIBILITY
densities()134 vector<result_type> densities() const {return __p_.densities();}
135
136 _LIBCPP_INLINE_VISIBILITY
param()137 param_type param() const {return __p_;}
138 _LIBCPP_INLINE_VISIBILITY
param(const param_type & __p)139 void param(const param_type& __p) {__p_ = __p;}
140
141 _LIBCPP_INLINE_VISIBILITY
min()142 result_type min() const {return __p_.__b_.front();}
143 _LIBCPP_INLINE_VISIBILITY
max()144 result_type max() const {return __p_.__b_.back();}
145
146 friend _LIBCPP_INLINE_VISIBILITY
147 bool operator==(const piecewise_linear_distribution& __x,
148 const piecewise_linear_distribution& __y)
149 {return __x.__p_ == __y.__p_;}
150 friend _LIBCPP_INLINE_VISIBILITY
151 bool operator!=(const piecewise_linear_distribution& __x,
152 const piecewise_linear_distribution& __y)
153 {return !(__x == __y);}
154
155 template <class _CharT, class _Traits, class _RT>
156 friend
157 basic_ostream<_CharT, _Traits>&
158 operator<<(basic_ostream<_CharT, _Traits>& __os,
159 const piecewise_linear_distribution<_RT>& __x);
160
161 template <class _CharT, class _Traits, class _RT>
162 friend
163 basic_istream<_CharT, _Traits>&
164 operator>>(basic_istream<_CharT, _Traits>& __is,
165 piecewise_linear_distribution<_RT>& __x);
166 };
167
168 template<class _RealType>
169 typename piecewise_linear_distribution<_RealType>::param_type &
170 piecewise_linear_distribution<_RealType>::param_type::operator=
171 (const param_type& __rhs)
172 {
173 // These can throw
174 __b_.reserve (__rhs.__b_.size ());
175 __densities_.reserve(__rhs.__densities_.size());
176 __areas_.reserve (__rhs.__areas_.size());
177
178 // These can not throw
179 __b_ = __rhs.__b_;
180 __densities_ = __rhs.__densities_;
181 __areas_ = __rhs.__areas_;
182 return *this;
183 }
184
185
186 template<class _RealType>
187 void
__init()188 piecewise_linear_distribution<_RealType>::param_type::__init()
189 {
190 __areas_.assign(__densities_.size() - 1, result_type());
191 result_type _Sp = 0;
192 for (size_t __i = 0; __i < __areas_.size(); ++__i)
193 {
194 __areas_[__i] = (__densities_[__i+1] + __densities_[__i]) *
195 (__b_[__i+1] - __b_[__i]) * .5;
196 _Sp += __areas_[__i];
197 }
198 for (size_t __i = __areas_.size(); __i > 1;)
199 {
200 --__i;
201 __areas_[__i] = __areas_[__i-1] / _Sp;
202 }
203 __areas_[0] = 0;
204 for (size_t __i = 1; __i < __areas_.size(); ++__i)
205 __areas_[__i] += __areas_[__i-1];
206 for (size_t __i = 0; __i < __densities_.size(); ++__i)
207 __densities_[__i] /= _Sp;
208 }
209
210 template<class _RealType>
param_type()211 piecewise_linear_distribution<_RealType>::param_type::param_type()
212 : __b_(2),
213 __densities_(2, 1.0),
214 __areas_(1, 0.0)
215 {
216 __b_[1] = 1;
217 }
218
219 template<class _RealType>
220 template<class _InputIteratorB, class _InputIteratorW>
param_type(_InputIteratorB __f_b,_InputIteratorB __l_b,_InputIteratorW __f_w)221 piecewise_linear_distribution<_RealType>::param_type::param_type(
222 _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
223 : __b_(__f_b, __l_b)
224 {
225 if (__b_.size() < 2)
226 {
227 __b_.resize(2);
228 __b_[0] = 0;
229 __b_[1] = 1;
230 __densities_.assign(2, 1.0);
231 __areas_.assign(1, 0.0);
232 }
233 else
234 {
235 __densities_.reserve(__b_.size());
236 for (size_t __i = 0; __i < __b_.size(); ++__i, ++__f_w)
237 __densities_.push_back(*__f_w);
238 __init();
239 }
240 }
241
242 #ifndef _LIBCPP_CXX03_LANG
243
244 template<class _RealType>
245 template<class _UnaryOperation>
param_type(initializer_list<result_type> __bl,_UnaryOperation __fw)246 piecewise_linear_distribution<_RealType>::param_type::param_type(
247 initializer_list<result_type> __bl, _UnaryOperation __fw)
248 : __b_(__bl.begin(), __bl.end())
249 {
250 if (__b_.size() < 2)
251 {
252 __b_.resize(2);
253 __b_[0] = 0;
254 __b_[1] = 1;
255 __densities_.assign(2, 1.0);
256 __areas_.assign(1, 0.0);
257 }
258 else
259 {
260 __densities_.reserve(__b_.size());
261 for (size_t __i = 0; __i < __b_.size(); ++__i)
262 __densities_.push_back(__fw(__b_[__i]));
263 __init();
264 }
265 }
266
267 #endif // _LIBCPP_CXX03_LANG
268
269 template<class _RealType>
270 template<class _UnaryOperation>
param_type(size_t __nw,result_type __xmin,result_type __xmax,_UnaryOperation __fw)271 piecewise_linear_distribution<_RealType>::param_type::param_type(
272 size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
273 : __b_(__nw == 0 ? 2 : __nw + 1)
274 {
275 size_t __n = __b_.size() - 1;
276 result_type __d = (__xmax - __xmin) / __n;
277 __densities_.reserve(__b_.size());
278 for (size_t __i = 0; __i < __n; ++__i)
279 {
280 __b_[__i] = __xmin + __i * __d;
281 __densities_.push_back(__fw(__b_[__i]));
282 }
283 __b_[__n] = __xmax;
284 __densities_.push_back(__fw(__b_[__n]));
285 __init();
286 }
287
288 template<class _RealType>
289 template<class _URNG>
290 _RealType
operator()291 piecewise_linear_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
292 {
293 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
294 typedef uniform_real_distribution<result_type> _Gen;
295 result_type __u = _Gen()(__g);
296 ptrdiff_t __k = _VSTD::upper_bound(__p.__areas_.begin(), __p.__areas_.end(),
297 __u) - __p.__areas_.begin() - 1;
298 __u -= __p.__areas_[__k];
299 const result_type __dk = __p.__densities_[__k];
300 const result_type __dk1 = __p.__densities_[__k+1];
301 const result_type __deltad = __dk1 - __dk;
302 const result_type __bk = __p.__b_[__k];
303 if (__deltad == 0)
304 return __u / __dk + __bk;
305 const result_type __bk1 = __p.__b_[__k+1];
306 const result_type __deltab = __bk1 - __bk;
307 return (__bk * __dk1 - __bk1 * __dk +
308 _VSTD::sqrt(__deltab * (__deltab * __dk * __dk + 2 * __deltad * __u))) /
309 __deltad;
310 }
311
312 template <class _CharT, class _Traits, class _RT>
313 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
314 operator<<(basic_ostream<_CharT, _Traits>& __os,
315 const piecewise_linear_distribution<_RT>& __x)
316 {
317 __save_flags<_CharT, _Traits> __lx(__os);
318 typedef basic_ostream<_CharT, _Traits> _OStream;
319 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
320 _OStream::scientific);
321 _CharT __sp = __os.widen(' ');
322 __os.fill(__sp);
323 size_t __n = __x.__p_.__b_.size();
324 __os << __n;
325 for (size_t __i = 0; __i < __n; ++__i)
326 __os << __sp << __x.__p_.__b_[__i];
327 __n = __x.__p_.__densities_.size();
328 __os << __sp << __n;
329 for (size_t __i = 0; __i < __n; ++__i)
330 __os << __sp << __x.__p_.__densities_[__i];
331 __n = __x.__p_.__areas_.size();
332 __os << __sp << __n;
333 for (size_t __i = 0; __i < __n; ++__i)
334 __os << __sp << __x.__p_.__areas_[__i];
335 return __os;
336 }
337
338 template <class _CharT, class _Traits, class _RT>
339 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
340 operator>>(basic_istream<_CharT, _Traits>& __is,
341 piecewise_linear_distribution<_RT>& __x)
342 {
343 typedef piecewise_linear_distribution<_RT> _Eng;
344 typedef typename _Eng::result_type result_type;
345 __save_flags<_CharT, _Traits> __lx(__is);
346 typedef basic_istream<_CharT, _Traits> _Istream;
347 __is.flags(_Istream::dec | _Istream::skipws);
348 size_t __n;
349 __is >> __n;
350 vector<result_type> __b(__n);
351 for (size_t __i = 0; __i < __n; ++__i)
352 __is >> __b[__i];
353 __is >> __n;
354 vector<result_type> __densities(__n);
355 for (size_t __i = 0; __i < __n; ++__i)
356 __is >> __densities[__i];
357 __is >> __n;
358 vector<result_type> __areas(__n);
359 for (size_t __i = 0; __i < __n; ++__i)
360 __is >> __areas[__i];
361 if (!__is.fail())
362 {
363 swap(__x.__p_.__b_, __b);
364 swap(__x.__p_.__densities_, __densities);
365 swap(__x.__p_.__areas_, __areas);
366 }
367 return __is;
368 }
369
370 _LIBCPP_END_NAMESPACE_STD
371
372 _LIBCPP_POP_MACROS
373
374 #endif // _LIBCPP___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H
375