NumCpp  2.9.0
A Templatized Header Only C++ Implementation of the Python NumPy Library
cross.hpp
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1 #pragma once
29 
30 #include <string>
31 
34 #include "NumCpp/Core/Shape.hpp"
35 #include "NumCpp/Core/Types.hpp"
36 #include "NumCpp/NdArray.hpp"
37 
38 namespace nc
39 {
40  //============================================================================
41  // Method Description:
51  template<typename dtype>
52  NdArray<dtype> cross(const NdArray<dtype>& inArray1, const NdArray<dtype>& inArray2, Axis inAxis = Axis::NONE)
53  {
55 
56  if (inArray1.shape() != inArray2.shape())
57  {
58  THROW_INVALID_ARGUMENT_ERROR("the input array dimensions are not consistant.");
59  }
60 
61  switch (inAxis)
62  {
63  case Axis::NONE:
64  {
65  const uint32 arraySize = inArray1.size();
66  if (arraySize != inArray2.size() || arraySize < 2 || arraySize > 3)
67  {
69  "incompatible dimensions for cross product (dimension must be 2 or 3)");
70  }
71 
72  NdArray<dtype> in1 = inArray1.flatten();
73  NdArray<dtype> in2 = inArray2.flatten();
74 
75  switch (arraySize)
76  {
77  case 2:
78  {
79  NdArray<dtype> returnArray = { in1[0] * in2[1] - in1[1] * in2[0] };
80  return returnArray;
81  }
82  case 3:
83  {
84  dtype i = in1[1] * in2[2] - in1[2] * in2[1];
85  dtype j = -(in1[0] * in2[2] - in1[2] * in2[0]);
86  dtype k = in1[0] * in2[1] - in1[1] * in2[0];
87 
88  NdArray<dtype> returnArray = { i, j, k };
89  return returnArray;
90  }
91  default:
92  {
93  THROW_INVALID_ARGUMENT_ERROR("Unimplemented array size.");
94  return {}; // get rid of compiler warning
95  }
96  }
97  }
98  case Axis::ROW:
99  {
100  const Shape arrayShape = inArray1.shape();
101  if (arrayShape != inArray2.shape() || arrayShape.rows < 2 || arrayShape.rows > 3)
102  {
104  "incompatible dimensions for cross product (dimension must be 2 or 3)");
105  }
106 
107  Shape returnArrayShape;
108  returnArrayShape.cols = arrayShape.cols;
109  if (arrayShape.rows == 2)
110  {
111  returnArrayShape.rows = 1;
112  }
113  else
114  {
115  returnArrayShape.rows = 3;
116  }
117 
118  NdArray<dtype> returnArray(returnArrayShape);
119  for (uint32 col = 0; col < arrayShape.cols; ++col)
120  {
121  const auto theCol = static_cast<int32>(col);
122  NdArray<dtype> vec1 = inArray1(inArray1.rSlice(), { theCol, theCol + 1 });
123  NdArray<dtype> vec2 = inArray2(inArray2.rSlice(), { theCol, theCol + 1 });
124  NdArray<dtype> vecCross = cross(vec1, vec2, Axis::NONE);
125 
126  returnArray.put({ 0, static_cast<int32>(returnArrayShape.rows) }, { theCol, theCol + 1 }, vecCross);
127  }
128 
129  return returnArray;
130  }
131  case Axis::COL:
132  {
133  const Shape arrayShape = inArray1.shape();
134  if (arrayShape != inArray2.shape() || arrayShape.cols < 2 || arrayShape.cols > 3)
135  {
137  "incompatible dimensions for cross product (dimension must be 2 or 3)");
138  }
139 
140  Shape returnArrayShape;
141  returnArrayShape.rows = arrayShape.rows;
142  if (arrayShape.cols == 2)
143  {
144  returnArrayShape.cols = 1;
145  }
146  else
147  {
148  returnArrayShape.cols = 3;
149  }
150 
151  NdArray<dtype> returnArray(returnArrayShape);
152  for (uint32 row = 0; row < arrayShape.rows; ++row)
153  {
154  const auto theRow = static_cast<int32>(row);
155  NdArray<dtype> vec1 = inArray1({ theRow, theRow + 1 }, inArray1.cSlice());
156  NdArray<dtype> vec2 = inArray2({ theRow, theRow + 1 }, inArray2.cSlice());
157  NdArray<dtype> vecCross = cross(vec1, vec2, Axis::NONE);
158 
159  returnArray.put({ theRow, theRow + 1 }, { 0, static_cast<int32>(returnArrayShape.cols) }, vecCross);
160  }
161 
162  return returnArray;
163  }
164  default:
165  {
166  THROW_INVALID_ARGUMENT_ERROR("Unimplemented axis type.");
167  return {}; // get rid of compiler warning
168  }
169  }
170  }
171 } // namespace nc
#define THROW_INVALID_ARGUMENT_ERROR(msg)
Definition: Error.hpp:36
#define STATIC_ASSERT_ARITHMETIC_OR_COMPLEX(dtype)
Definition: StaticAsserts.hpp:49
Holds 1D and 2D arrays, the main work horse of the NumCpp library.
Definition: NdArrayCore.hpp:72
NdArray< dtype > & put(int32 inIndex, value_type inValue)
Definition: NdArrayCore.hpp:3479
size_type size() const noexcept
Definition: NdArrayCore.hpp:4105
NdArray< dtype > flatten() const
Definition: NdArrayCore.hpp:2648
Slice cSlice(int32 inStartIdx=0, uint32 inStepSize=1) const noexcept
Definition: NdArrayCore.hpp:969
Shape shape() const noexcept
Definition: NdArrayCore.hpp:4092
Slice rSlice(int32 inStartIdx=0, uint32 inStepSize=1) const noexcept
Definition: NdArrayCore.hpp:983
A Shape Class for NdArrays.
Definition: Core/Shape.hpp:41
uint32 rows
Definition: Core/Shape.hpp:44
uint32 cols
Definition: Core/Shape.hpp:45
constexpr auto j
Definition: Constants.hpp:45
Definition: Coordinate.hpp:45
NdArray< dtype > cross(const NdArray< dtype > &inArray1, const NdArray< dtype > &inArray2, Axis inAxis=Axis::NONE)
Definition: cross.hpp:52
Axis
Enum To describe an axis.
Definition: Types.hpp:47
std::int32_t int32
Definition: Types.hpp:36
std::uint32_t uint32
Definition: Types.hpp:40