HDF5 重新缩放数据集最大维度

Question

我已经创建了一个分块布局的数据集，我已经确定了数据集的最大大小

DataSpace *dataspace = new DataSpace (2, dims, maxdims)//maxdims equal to dims
// Modify dataset creation property to enable chunking
DSetCreatPropList prop;
prop.setChunk(2, chunk_dims);

然后我在里面记录了一些数据。最近我需要调整这个数据集的大小，但是新的大小超过了我在开始时确定的最大大小，这导致每次我尝试调整数据集大小时都会出现异常

dataset->extend(new_size); //New size

有没有一种方法可以在不丢失记录数据的情况下扩展数据集的最大维度。如果没有，有没有办法用另一个包含我的数据并具有新的最大大小的数据集来覆盖数据集？

Answer 1

选项 ::extend() 仅适用于可扩展数据集 (link)。

如果您的数据集是使用最大大小创建的，则无法将其更改为可扩展的数据集。您必须将内容复制到创建为无限制的新数据集。

这里有一个取自 hdf 网站 (link) 的示例。

/*
 *   This example shows how to work with extendible dataset.
 *   In the current version of the library dataset MUST be
 *   chunked.
 */
#ifdef OLD_HEADER_FILENAME
#include <iostream.h>
#else
#include <iostream>
#endif
#include <string>
#ifndef H5_NO_NAMESPACE
#ifndef H5_NO_STD
    using std::cout;
    using std::endl;
#endif  // H5_NO_STD
#endif
#include "H5Cpp.h"
#ifndef H5_NO_NAMESPACE
    using namespace H5;
#endif
const H5std_string FILE_NAME( "SDSextendible.h5" );
const H5std_string DATASET_NAME( "ExtendibleArray" );
const int      NX = 10;
const int      NY = 5;
const int      RANK = 2;
int main (void)
{
   //Try block to detect exceptions raised by any of the calls inside it
   try
   {
      /*
       * Turn off the auto-printing when failure occurs so that we can
       * handle the errors appropriately
       */
      Exception::dontPrint();

      //Create the data space with unlimited dimensions.
      hsize_t      dims[2]  = { 3, 3};  // dataset dimensions at creation
      hsize_t      maxdims[2] = {H5S_UNLIMITED, H5S_UNLIMITED};
      DataSpace mspace1( RANK, dims, maxdims);

      //Create a new file. If file exists its contents will be overwritten.
      H5File file( FILE_NAME, H5F_ACC_TRUNC );

      //Modify dataset creation properties, i.e. enable chunking.          
      DSetCreatPropList cparms;
      hsize_t      chunk_dims[2] ={2, 5};
      cparms.setChunk( RANK, chunk_dims );

      //Set fill value for the dataset          
      int fill_val = 0;
      cparms.setFillValue( PredType::NATIVE_INT, &fill_val);

      //Create a new dataset within the file using cparms creation properties.
      DataSet dataset = file.createDataSet( DATASET_NAME, PredType::NATIVE_INT, mspace1, cparms);

      //Extend the dataset. This call assures that dataset is at least 3 x 3.
      hsize_t      size[2];
      size[0]   = 3;
      size[1]   = 3;
      dataset.extend( size );

      //Select a hyperslab.
      DataSpace fspace1 = dataset.getSpace ();
      hsize_t     offset[2];
      offset[0] = 0;
      offset[1] = 0;
      hsize_t      dims1[2] = { 3, 3};            /* data1 dimensions */
      fspace1.selectHyperslab( H5S_SELECT_SET, dims1, offset );

      //Write the data to the hyperslab.          
      int       data1[3][3] = { {1, 1, 1},       /* data to write */
                {1, 1, 1},
                {1, 1, 1} };
      dataset.write( data1, PredType::NATIVE_INT, mspace1, fspace1 );

      //Extend the dataset. Dataset becomes 10 x 3.           
      hsize_t   dims2[2] = { 7, 1};            /* data2 dimensions */
      dims[0]   = dims1[0] + dims2[0];
      size[0]   = dims[0];
      size[1]   = dims[1];
      dataset.extend( size );

      //Select a hyperslab.         
      DataSpace fspace2 = dataset.getSpace ();
      offset[0] = 3;
      offset[1] = 0;
      fspace2.selectHyperslab( H5S_SELECT_SET, dims2, offset );

      //Define memory space
      DataSpace mspace2( RANK, dims2 );

      //Write the data to the hyperslab.
      int  data2[7]    = { 2, 2, 2, 2, 2, 2, 2};
      dataset.write( data2, PredType::NATIVE_INT, mspace2, fspace2 );

      //Extend the dataset. Dataset becomes 10 x 5.
      hsize_t   dims3[2] = { 2, 2};            /* data3 dimensions */
      dims[1]   = dims1[1] + dims3[1];
      size[0]   = dims[0];
      size[1]   = dims[1];
      dataset.extend( size );

      //Select a hyperslab          
      DataSpace fspace3 = dataset.getSpace ();
      offset[0] = 0;
      offset[1] = 3;
      fspace3.selectHyperslab( H5S_SELECT_SET, dims3, offset );

      //Define memory space.
      DataSpace mspace3( RANK, dims3 );

      //Write the data to the hyperslab.          
      int         data3[2][2] = { {3, 3}, {3, 3} };
      dataset.write( data3, PredType::NATIVE_INT, mspace3, fspace3 );

      //Read the data from this dataset and display it.          
      int i, j;
      int data_out[NX][NY];
      for (i = 0; i < NX; i++)
      {
         for (j = 0; j < NY; j++)
            data_out[i][j] = 0;
      }
      dataset.read( data_out, PredType::NATIVE_INT );
      /*
       * Resulting dataset
       *
       *     1 1 1 3 3
       *     1 1 1 3 3
       *     1 1 1 0 0
       *     2 0 0 0 0
       *     2 0 0 0 0
       *     2 0 0 0 0
       *     2 0 0 0 0
       *     2 0 0 0 0
       *     2 0 0 0 0
       *     2 0 0 0 0
       */

      //Display the result.          
      for (i=0; i < NX; i++)
      {
          for(j=0; j < NY; j++)
             cout << data_out[i][j] << "  ";
          cout << endl;
      }
   }  // end of try block
   // catch failure caused by the H5File operations
   catch( FileIException error )
   {
      error.printError();
      return -1;
   }
   // catch failure caused by the DataSet operations
   catch( DataSetIException error )
   {
      error.printError();
      return -1;
   }
   // catch failure caused by the DataSpace operations
   catch( DataSpaceIException error )
   {
      error.printError();
      return -1;
   }
   // catch failure caused by the DataSpace operations
   catch( DataTypeIException error )
   {
      error.printError();
      return -1;
   }
   return 0;
}

HDF5 重新缩放数据集最大维度

HDF5 Rescale Dataset Maximum Dimension

c++

hdf5