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MnistDatabase Class Reference

#include <MnistDatabase.hpp>

Public Types

using DataType = float
 
using TTestCaseData = ClassifierTestCaseData< DataType >
 

Public Member Functions

 MnistDatabase (const std::string &binaryFileDirectory, bool scaleValues=false)
 
std::unique_ptr< TTestCaseDataGetTestCaseData (unsigned int testCaseId)
 

Detailed Description

Definition at line 12 of file MnistDatabase.hpp.

Member Typedef Documentation

◆ DataType

using DataType = float

Definition at line 15 of file MnistDatabase.hpp.

◆ TTestCaseData

Definition at line 16 of file MnistDatabase.hpp.

Constructor & Destructor Documentation

◆ MnistDatabase()

MnistDatabase ( const std::string &  binaryFileDirectory,
bool  scaleValues = false 
)
explicit

Definition at line 21 of file MnistDatabase.cpp.

22  : m_BinaryDirectory(binaryFileDirectory)
23  , m_ScaleValues(scaleValues)
24 {
25 }

Member Function Documentation

◆ GetTestCaseData()

std::unique_ptr< MnistDatabase::TTestCaseData > GetTestCaseData ( unsigned int  testCaseId)

Definition at line 27 of file MnistDatabase.cpp.

References ARMNN_LOG, EndianSwap(), and g_kMnistImageByteSize.

28 {
29  std::vector<unsigned char> I(g_kMnistImageByteSize);
30  unsigned int label = 0;
31 
32  std::string imagePath = m_BinaryDirectory + std::string("t10k-images.idx3-ubyte");
33  std::string labelPath = m_BinaryDirectory + std::string("t10k-labels.idx1-ubyte");
34 
35  std::ifstream imageStream(imagePath, std::ios::binary);
36  std::ifstream labelStream(labelPath, std::ios::binary);
37 
38  if (!imageStream.is_open())
39  {
40  ARMNN_LOG(fatal) << "Failed to load " << imagePath;
41  return nullptr;
42  }
43  if (!labelStream.is_open())
44  {
45  ARMNN_LOG(fatal) << "Failed to load " << imagePath;
46  return nullptr;
47  }
48 
49  unsigned int magic, num, row, col;
50 
51  // Checks the files have the correct header.
52  imageStream.read(reinterpret_cast<char*>(&magic), sizeof(magic));
53  if (magic != 0x03080000)
54  {
55  ARMNN_LOG(fatal) << "Failed to read " << imagePath;
56  return nullptr;
57  }
58  labelStream.read(reinterpret_cast<char*>(&magic), sizeof(magic));
59  if (magic != 0x01080000)
60  {
61  ARMNN_LOG(fatal) << "Failed to read " << labelPath;
62  return nullptr;
63  }
64 
65  // Endian swaps the image and label file - all the integers in the files are stored in MSB first(high endian)
66  // format, hence it needs to flip the bytes of the header if using it on Intel processors or low-endian machines
67  labelStream.read(reinterpret_cast<char*>(&num), sizeof(num));
68  imageStream.read(reinterpret_cast<char*>(&num), sizeof(num));
69  EndianSwap(num);
70  imageStream.read(reinterpret_cast<char*>(&row), sizeof(row));
71  EndianSwap(row);
72  imageStream.read(reinterpret_cast<char*>(&col), sizeof(col));
73  EndianSwap(col);
74 
75  // Reads image and label into memory.
76  imageStream.seekg(testCaseId * g_kMnistImageByteSize, std::ios_base::cur);
77  imageStream.read(reinterpret_cast<char*>(&I[0]), g_kMnistImageByteSize);
78  labelStream.seekg(testCaseId, std::ios_base::cur);
79  labelStream.read(reinterpret_cast<char*>(&label), 1);
80 
81  if (!imageStream.good())
82  {
83  ARMNN_LOG(fatal) << "Failed to read " << imagePath;
84  return nullptr;
85  }
86  if (!labelStream.good())
87  {
88  ARMNN_LOG(fatal) << "Failed to read " << labelPath;
89  return nullptr;
90  }
91 
92  std::vector<float> inputImageData;
93  inputImageData.resize(g_kMnistImageByteSize);
94 
95  for (unsigned int i = 0; i < col * row; ++i)
96  {
97  inputImageData[i] = boost::numeric_cast<float>(I[i]);
98 
99  if(m_ScaleValues)
100  {
101  inputImageData[i] /= 255.0f;
102  }
103  }
104 
105  return std::make_unique<TTestCaseData>(label, std::move(inputImageData));
106 }
#define ARMNN_LOG(severity)
Definition: Logging.hpp:163
constexpr int g_kMnistImageByteSize
void EndianSwap(unsigned int &x)

The documentation for this class was generated from the following files: