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_CONSTANT_DISTRIBUTION_H
10 #define _LIBCPP___CXX03___RANDOM_PIECEWISE_CONSTANT_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/iosfwd>
17 #include <__cxx03/numeric>
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_constant_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_constant_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 template <class _UnaryOperation>
50 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);
51 _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;
52 _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);
53
intervals()54 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }
densities()55 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }
56
57 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
58 return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;
59 }
60 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
61
62 private:
63 _LIBCPP_HIDE_FROM_ABI void __init();
64
65 friend class piecewise_constant_distribution;
66
67 template <class _CharT, class _Traits, class _RT>
68 friend basic_ostream<_CharT, _Traits>&
69 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);
70
71 template <class _CharT, class _Traits, class _RT>
72 friend basic_istream<_CharT, _Traits>&
73 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);
74 };
75
76 private:
77 param_type __p_;
78
79 public:
80 // constructor and reset functions
piecewise_constant_distribution()81 _LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution() {}
82 template <class _InputIteratorB, class _InputIteratorW>
83 _LIBCPP_HIDE_FROM_ABI
piecewise_constant_distribution(_InputIteratorB __f_b,_InputIteratorB __l_b,_InputIteratorW __f_w)84 piecewise_constant_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
85 : __p_(__f_b, __l_b, __f_w) {}
86
87 template <class _UnaryOperation>
88 _LIBCPP_HIDE_FROM_ABI
piecewise_constant_distribution(size_t __nw,result_type __xmin,result_type __xmax,_UnaryOperation __fw)89 piecewise_constant_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
90 : __p_(__nw, __xmin, __xmax, __fw) {}
91
piecewise_constant_distribution(const param_type & __p)92 _LIBCPP_HIDE_FROM_ABI explicit piecewise_constant_distribution(const param_type& __p) : __p_(__p) {}
93
reset()94 _LIBCPP_HIDE_FROM_ABI void reset() {}
95
96 // generating functions
97 template <class _URNG>
operator()98 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
99 return (*this)(__g, __p_);
100 }
101 template <class _URNG>
102 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
103
104 // property functions
intervals()105 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }
densities()106 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }
107
param()108 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
param(const param_type & __p)109 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
110
min()111 _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }
max()112 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }
113
114 friend _LIBCPP_HIDE_FROM_ABI bool
115 operator==(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {
116 return __x.__p_ == __y.__p_;
117 }
118 friend _LIBCPP_HIDE_FROM_ABI bool
119 operator!=(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {
120 return !(__x == __y);
121 }
122
123 template <class _CharT, class _Traits, class _RT>
124 friend basic_ostream<_CharT, _Traits>&
125 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);
126
127 template <class _CharT, class _Traits, class _RT>
128 friend basic_istream<_CharT, _Traits>&
129 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);
130 };
131
132 template <class _RealType>
133 typename piecewise_constant_distribution<_RealType>::param_type&
134 piecewise_constant_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {
135 // These can throw
136 __b_.reserve(__rhs.__b_.size());
137 __densities_.reserve(__rhs.__densities_.size());
138 __areas_.reserve(__rhs.__areas_.size());
139
140 // These can not throw
141 __b_ = __rhs.__b_;
142 __densities_ = __rhs.__densities_;
143 __areas_ = __rhs.__areas_;
144 return *this;
145 }
146
147 template <class _RealType>
__init()148 void piecewise_constant_distribution<_RealType>::param_type::__init() {
149 // __densities_ contains non-normalized areas
150 result_type __total_area = std::accumulate(__densities_.begin(), __densities_.end(), result_type());
151 for (size_t __i = 0; __i < __densities_.size(); ++__i)
152 __densities_[__i] /= __total_area;
153 // __densities_ contains normalized areas
154 __areas_.assign(__densities_.size(), result_type());
155 std::partial_sum(__densities_.begin(), __densities_.end() - 1, __areas_.begin() + 1);
156 // __areas_ contains partial sums of normalized areas: [0, __densities_ - 1]
157 __densities_.back() = 1 - __areas_.back(); // correct round off error
158 for (size_t __i = 0; __i < __densities_.size(); ++__i)
159 __densities_[__i] /= (__b_[__i + 1] - __b_[__i]);
160 // __densities_ now contains __densities_
161 }
162
163 template <class _RealType>
param_type()164 piecewise_constant_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(1, 1.0), __areas_(1, 0.0) {
165 __b_[1] = 1;
166 }
167
168 template <class _RealType>
169 template <class _InputIteratorB, class _InputIteratorW>
param_type(_InputIteratorB __f_b,_InputIteratorB __l_b,_InputIteratorW __f_w)170 piecewise_constant_distribution<_RealType>::param_type::param_type(
171 _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)
172 : __b_(__f_b, __l_b) {
173 if (__b_.size() < 2) {
174 __b_.resize(2);
175 __b_[0] = 0;
176 __b_[1] = 1;
177 __densities_.assign(1, 1.0);
178 __areas_.assign(1, 0.0);
179 } else {
180 __densities_.reserve(__b_.size() - 1);
181 for (size_t __i = 0; __i < __b_.size() - 1; ++__i, ++__f_w)
182 __densities_.push_back(*__f_w);
183 __init();
184 }
185 }
186
187 template <class _RealType>
188 template <class _UnaryOperation>
param_type(size_t __nw,result_type __xmin,result_type __xmax,_UnaryOperation __fw)189 piecewise_constant_distribution<_RealType>::param_type::param_type(
190 size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)
191 : __b_(__nw == 0 ? 2 : __nw + 1) {
192 size_t __n = __b_.size() - 1;
193 result_type __d = (__xmax - __xmin) / __n;
194 __densities_.reserve(__n);
195 for (size_t __i = 0; __i < __n; ++__i) {
196 __b_[__i] = __xmin + __i * __d;
197 __densities_.push_back(__fw(__b_[__i] + __d * .5));
198 }
199 __b_[__n] = __xmax;
200 __init();
201 }
202
203 template <class _RealType>
204 template <class _URNG>
operator()205 _RealType piecewise_constant_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
206 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
207 typedef uniform_real_distribution<result_type> _Gen;
208 result_type __u = _Gen()(__g);
209 ptrdiff_t __k = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;
210 return (__u - __p.__areas_[__k]) / __p.__densities_[__k] + __p.__b_[__k];
211 }
212
213 template <class _CharT, class _Traits, class _RT>
214 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
215 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x) {
216 __save_flags<_CharT, _Traits> __lx(__os);
217 typedef basic_ostream<_CharT, _Traits> _OStream;
218 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
219 _CharT __sp = __os.widen(' ');
220 __os.fill(__sp);
221 size_t __n = __x.__p_.__b_.size();
222 __os << __n;
223 for (size_t __i = 0; __i < __n; ++__i)
224 __os << __sp << __x.__p_.__b_[__i];
225 __n = __x.__p_.__densities_.size();
226 __os << __sp << __n;
227 for (size_t __i = 0; __i < __n; ++__i)
228 __os << __sp << __x.__p_.__densities_[__i];
229 __n = __x.__p_.__areas_.size();
230 __os << __sp << __n;
231 for (size_t __i = 0; __i < __n; ++__i)
232 __os << __sp << __x.__p_.__areas_[__i];
233 return __os;
234 }
235
236 template <class _CharT, class _Traits, class _RT>
237 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
238 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x) {
239 typedef piecewise_constant_distribution<_RT> _Eng;
240 typedef typename _Eng::result_type result_type;
241 __save_flags<_CharT, _Traits> __lx(__is);
242 typedef basic_istream<_CharT, _Traits> _Istream;
243 __is.flags(_Istream::dec | _Istream::skipws);
244 size_t __n;
245 __is >> __n;
246 vector<result_type> __b(__n);
247 for (size_t __i = 0; __i < __n; ++__i)
248 __is >> __b[__i];
249 __is >> __n;
250 vector<result_type> __densities(__n);
251 for (size_t __i = 0; __i < __n; ++__i)
252 __is >> __densities[__i];
253 __is >> __n;
254 vector<result_type> __areas(__n);
255 for (size_t __i = 0; __i < __n; ++__i)
256 __is >> __areas[__i];
257 if (!__is.fail()) {
258 swap(__x.__p_.__b_, __b);
259 swap(__x.__p_.__densities_, __densities);
260 swap(__x.__p_.__areas_, __areas);
261 }
262 return __is;
263 }
264
265 _LIBCPP_END_NAMESPACE_STD
266
267 _LIBCPP_POP_MACROS
268
269 #endif // _LIBCPP___CXX03___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H
270