NumCpp  1.0
A C++ implementation of the Python Numpy library
stdev.hpp
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1 #pragma once
30 
31 #include "NumCpp/NdArray.hpp"
32 #include "NumCpp/Core/Types.hpp"
34 #include "NumCpp/Utils/sqr.hpp"
35 
36 #include <algorithm>
37 #include <cmath>
38 #include <complex>
39 
40 namespace nc
41 {
42  //============================================================================
43  // Method Description:
53  template<typename dtype>
54  NdArray<double> stdev(const NdArray<dtype>& inArray, Axis inAxis = Axis::NONE)
55  {
57 
58  double meanValue = 0.0;
59  double sum = 0.0;
60 
61  const auto function = [&sum, &meanValue](dtype value) -> void
62  {
63  sum += utils::sqr(static_cast<double>(value) - meanValue);
64  };
65 
66  switch (inAxis)
67  {
68  case Axis::NONE:
69  {
70  meanValue = mean(inArray, inAxis).item();
71  std::for_each(inArray.cbegin(), inArray.cend(), function);
72 
73  NdArray<double> returnArray = { std::sqrt(sum / inArray.size()) };
74  return returnArray;
75  }
76  case Axis::COL:
77  {
78  NdArray<double> meanValueArray = mean(inArray, inAxis);
79  NdArray<double> returnArray(1, inArray.numRows());
80  for (uint32 row = 0; row < inArray.numRows(); ++row)
81  {
82  meanValue = meanValueArray[row];
83  sum = 0.0;
84  std::for_each(inArray.cbegin(row), inArray.cend(row), function);
85 
86  returnArray(0, row) = std::sqrt(sum / inArray.numCols());
87  }
88 
89  return returnArray;
90  }
91  case Axis::ROW:
92  {
93  NdArray<double> meanValueArray = mean(inArray, inAxis);
94  NdArray<dtype> transposedArray = inArray.transpose();
95  NdArray<double> returnArray(1, transposedArray.numRows());
96  for (uint32 row = 0; row < transposedArray.numRows(); ++row)
97  {
98  meanValue = meanValueArray[row];
99  sum = 0.0;
100  std::for_each(transposedArray.cbegin(row), transposedArray.cend(row), function);
101 
102  returnArray(0, row) = std::sqrt(sum / transposedArray.numCols());
103  }
104 
105  return returnArray;
106  }
107  default:
108  {
109  return NdArray<double>(); // get rid of compiler warning
110  }
111  }
112  }
113 
114  //============================================================================
115  // Method Description:
125  template<typename dtype>
126  NdArray<std::complex<double>> stdev(const NdArray<std::complex<dtype>>& inArray, Axis inAxis = Axis::NONE)
127  {
129 
130  std::complex<double> meanValue(0.0, 0.0);
131  std::complex<double> sum(0.0, 0.0);
132 
133  const auto function = [&sum, &meanValue](std::complex<dtype> value) -> void
134  {
135  sum += utils::sqr(complex_cast<double>(value) - meanValue);
136  };
137 
138  switch (inAxis)
139  {
140  case Axis::NONE:
141  {
142  meanValue = mean(inArray, inAxis).item();
143  std::for_each(inArray.cbegin(), inArray.cend(), function);
144 
145  NdArray<std::complex<double>> returnArray = { std::sqrt(sum / static_cast<double>(inArray.size())) };
146  return returnArray;
147  }
148  case Axis::COL:
149  {
150  NdArray<std::complex<double>> meanValueArray = mean(inArray, inAxis);
151  NdArray<std::complex<double>> returnArray(1, inArray.numRows());
152  for (uint32 row = 0; row < inArray.numRows(); ++row)
153  {
154  meanValue = meanValueArray[row];
155  sum = std::complex<double>(0.0, 0.0);
156  std::for_each(inArray.cbegin(row), inArray.cend(row), function);
157 
158  returnArray(0, row) = std::sqrt(sum / static_cast<double>(inArray.numCols()));
159  }
160 
161  return returnArray;
162  }
163  case Axis::ROW:
164  {
165  NdArray<std::complex<double>> meanValueArray = mean(inArray, inAxis);
166  NdArray<std::complex<dtype>> transposedArray = inArray.transpose();
167  NdArray<std::complex<double>> returnArray(1, transposedArray.numRows());
168  for (uint32 row = 0; row < transposedArray.numRows(); ++row)
169  {
170  meanValue = meanValueArray[row];
171  sum = std::complex<double>(0.0, 0.0);
172  std::for_each(transposedArray.cbegin(row), transposedArray.cend(row), function);
173 
174  returnArray(0, row) = std::sqrt(sum / static_cast<double>(transposedArray.numCols()));
175  }
176 
177  return returnArray;
178  }
179  default:
180  {
181  return NdArray<std::complex<double>>(); // get rid of compiler warning
182  }
183  }
184  }
185 }
nc::NdArray::item
value_type item() const
Definition: NdArrayCore.hpp:2950
nc::Axis::NONE
@ NONE
STATIC_ASSERT_ARITHMETIC
#define STATIC_ASSERT_ARITHMETIC(dtype)
Definition: StaticAsserts.hpp:38
nc::Axis::ROW
@ ROW
nc::sqrt
auto sqrt(dtype inValue) noexcept
Definition: sqrt.hpp:51
nc::stl_algorithms::for_each
void for_each(InputIt first, InputIt last, UnaryFunction f) noexcept
Definition: StlAlgorithms.hpp:214
nc::mean
NdArray< double > mean(const NdArray< dtype > &inArray, Axis inAxis=Axis::NONE)
Definition: mean.hpp:54
nc::NdArray::transpose
NdArray< dtype > transpose() const
Definition: NdArrayCore.hpp:4591
nc::NdArray< double >
nc::uint32
std::uint32_t uint32
Definition: Types.hpp:41
nc::NdArray::numCols
uint32 numCols() const noexcept
Definition: NdArrayCore.hpp:3415
NdArray.hpp
nc::NdArray::size
size_type size() const noexcept
Definition: NdArrayCore.hpp:4310
nc::sum
NdArray< dtype > sum(const NdArray< dtype > &inArray, Axis inAxis=Axis::NONE)
Definition: sum.hpp:48
nc::NdArray::cend
const_iterator cend() const noexcept
Definition: NdArrayCore.hpp:1491
nc::Axis
Axis
Enum To describe an axis.
Definition: Types.hpp:47
nc::stdev
NdArray< double > stdev(const NdArray< dtype > &inArray, Axis inAxis=Axis::NONE)
Definition: stdev.hpp:54
nc
Definition: Coordinate.hpp:45
sqr.hpp
nc::NdArray::cbegin
const_iterator cbegin() const noexcept
Definition: NdArrayCore.hpp:1147
nc::utils::sqr
constexpr dtype sqr(dtype inValue) noexcept
Definition: sqr.hpp:45
Types.hpp
nc::NdArray::numRows
uint32 numRows() const noexcept
Definition: NdArrayCore.hpp:3428
nc::Axis::COL
@ COL
mean.hpp