正如标题所说，我想从c ++中读取hdf5文件中的数据集。数据集是用h5py编写的。它包含一个复杂数字的numpy数组。
我可以正确检测数组的总维数
using namespace H5;
std::string file_name = "/path/to/my/file.hdf5";
std::string dataset_name = "dataset_name";
H5File file(file_name, H5F_ACC_RDONLY);
DataSet dset = file.openDataSet(dataset_name);
DataSpace dspace = dset.getSpace();
int size = dspace.getSimpleExtentNpoints();
我可以准备一个vector
std::vector<std::complex<double>> out_vector(size);
如何阅读数据集？
dset.read(out_vector.data(), ???);
答案 0 :(得分：0)
HDF5 API没有复杂的DataType。
python API也没有。但是，h5py会自动创建一个包含双精度对的复合类型。 h5dump /path/to/my/file.hdf5显示了它：
DATATYPE H5T_COMPOUND {
H5T_IEEE_F64LE "r";
H5T_IEEE_F64LE "i"
}
在c ++中，必须手动创建兼容的复合数据类型。例如：
CompType complex_data_type(sizeof(out_vector[0]));
complex_data_type.insertMember( "r", 0, PredType::NATIVE_DOUBLE);
complex_data_type.insertMember( "i", sizeof(double), PredType::NATIVE_DOUBLE);
现在可以阅读DataSet
dset.read(out_vector.data(), complex_data_type);
答案 1 :(得分：0)
https://support.hdfgroup.org/上有一个示例，说明如何处理HDF5 C ++ API 1.10.1的复合数据类型（不仅复杂）：
https://support.hdfgroup.org/HDF5/doc/cpplus_RM/compound_8cpp-example.html
有必要为复合物定义复合类型：
typedef struct complex_type{
double r;
double i;
} complex_type;
H5::CompType complex_compound( sizeof(complex_type) );
complex_compound.insertMember("r", HOFFSET(complex_type, r), H5::PredType::NATIVE_DOUBLE);
complex_compound.insertMember("i", HOFFSET(complex_type, i), H5::PredType::NATIVE_DOUBLE);
这是完整的代码：
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This example shows how to create a compound datatype,
* write an array which has the compound datatype to the file,
* and read back fields' subsets.
*/
#ifdef OLD_HEADER_FILENAME
#include <iostream.h>
#else
#include <iostream>
#endif
using std::cout;
using std::endl;
#include <string>
#include "H5Cpp.h"
using namespace H5;
const H5std_string FILE_NAME( "SDScompound.h5" );
const H5std_string DATASET_NAME( "ArrayOfStructures" );
const H5std_string MEMBER1( "a_name" );
const H5std_string MEMBER2( "b_name" );
const H5std_string MEMBER3( "c_name" );
const int LENGTH = 10;
const int RANK = 1;
int main(void)
{
/* First structure and dataset*/
typedef struct s1_t {
int a;
float b;
double c;
} s1_t;
/* Second structure (subset of s1_t) and dataset*/
typedef struct s2_t {
double c;
int a;
} s2_t;
// Try block to detect exceptions raised by any of the calls inside it
try
{
/*
* Initialize the data
*/
int i;
s1_t s1[LENGTH];
for (i = 0; i< LENGTH; i++)
{
s1[i].a = i;
s1[i].b = i*i;
s1[i].c = 1./(i+1);
}
/*
* Turn off the auto-printing when failure occurs so that we can
* handle the errors appropriately
*/
Exception::dontPrint();
/*
* Create the data space.
*/
hsize_t dim[] = {LENGTH}; /* Dataspace dimensions */
DataSpace space( RANK, dim );
/*
* Create the file.
*/
H5File* file = new H5File( FILE_NAME, H5F_ACC_TRUNC );
/*
* Create the memory datatype.
*/
CompType mtype1( sizeof(s1_t) );
mtype1.insertMember( MEMBER1, HOFFSET(s1_t, a), PredType::NATIVE_INT);
mtype1.insertMember( MEMBER3, HOFFSET(s1_t, c), PredType::NATIVE_DOUBLE);
mtype1.insertMember( MEMBER2, HOFFSET(s1_t, b), PredType::NATIVE_FLOAT);
/*
* Create the dataset.
*/
DataSet* dataset;
dataset = new DataSet(file->createDataSet(DATASET_NAME, mtype1, space));
/*
* Write data to the dataset;
*/
dataset->write( s1, mtype1 );
/*
* Release resources
*/
delete dataset;
delete file;
/*
* Open the file and the dataset.
*/
file = new H5File( FILE_NAME, H5F_ACC_RDONLY );
dataset = new DataSet (file->openDataSet( DATASET_NAME ));
/*
* Create a datatype for s2
*/
CompType mtype2( sizeof(s2_t) );
mtype2.insertMember( MEMBER3, HOFFSET(s2_t, c), PredType::NATIVE_DOUBLE);
mtype2.insertMember( MEMBER1, HOFFSET(s2_t, a), PredType::NATIVE_INT);
/*
* Read two fields c and a from s1 dataset. Fields in the file
* are found by their names "c_name" and "a_name".
*/
s2_t s2[LENGTH];
dataset->read( s2, mtype2 );
/*
* Display the fields
*/
cout << endl << "Field c : " << endl;
for( i = 0; i < LENGTH; i++)
cout << s2[i].c << " ";
cout << endl;
cout << endl << "Field a : " << endl;
for( i = 0; i < LENGTH; i++)
cout << s2[i].a << " ";
cout << endl;
/*
* Create a datatype for s3.
*/
CompType mtype3( sizeof(float) );
mtype3.insertMember( MEMBER2, 0, PredType::NATIVE_FLOAT);
/*
* Read field b from s1 dataset. Field in the file is found by its name.
*/
float s3[LENGTH]; // Third "structure" - used to read float field of s1
dataset->read( s3, mtype3 );
/*
* Display the field
*/
cout << endl << "Field b : " << endl;
for( i = 0; i < LENGTH; i++)
cout << s3[i] << " ";
cout << endl;
/*
* Release resources
*/
delete dataset;
delete file;
} // 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;
}