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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* 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 program creates a group in the file and two datasets in the group.
* Hard link to the group object is created and one of the datasets is accessed
* under new name.
* Iterator functions are used to find information about the objects
* in the root group and in the created group.
*/
#include "hdf5.h"
#define H5FILE_NAME "group.h5"
#define RANK 2
static herr_t file_info(hid_t loc_id, const char *name, const H5L_info2_t *linfo,
void *opdata); /* Link iteration operator function */
static herr_t group_info(hid_t loc_id, const char *name, const H5L_info2_t *linfo,
void *opdata); /* Link iteration operator function */
int
main(void)
{
hid_t file;
hid_t grp;
hid_t dataset, dataspace;
hid_t plist;
herr_t status;
hsize_t dims[2];
hsize_t cdims[2];
int idx_f, idx_g;
/*
* Create a file.
*/
file = H5Fcreate(H5FILE_NAME, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create a group in the file.
*/
grp = H5Gcreate2(file, "/Data", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create dataset "Compressed Data" in the group using absolute
* name. Dataset creation property list is modified to use
* GZIP compression with the compression effort set to 6.
* Note that compression can be used only when dataset is chunked.
*/
dims[0] = 1000;
dims[1] = 20;
cdims[0] = 20;
cdims[1] = 20;
dataspace = H5Screate_simple(RANK, dims, NULL);
plist = H5Pcreate(H5P_DATASET_CREATE);
H5Pset_chunk(plist, 2, cdims);
H5Pset_deflate(plist, 6);
dataset =
H5Dcreate2(file, "/Data/Compressed_Data", H5T_NATIVE_INT, dataspace, H5P_DEFAULT, plist, H5P_DEFAULT);
/*
* Close the first dataset .
*/
H5Sclose(dataspace);
H5Dclose(dataset);
/*
* Create the second dataset.
*/
dims[0] = 500;
dims[1] = 20;
dataspace = H5Screate_simple(RANK, dims, NULL);
dataset = H5Dcreate2(file, "/Data/Float_Data", H5T_NATIVE_FLOAT, dataspace, H5P_DEFAULT, H5P_DEFAULT,
H5P_DEFAULT);
/*
*Close the second dataset and file.
*/
H5Sclose(dataspace);
H5Dclose(dataset);
H5Pclose(plist);
H5Gclose(grp);
H5Fclose(file);
/*
* Now reopen the file and group in the file.
*/
file = H5Fopen(H5FILE_NAME, H5F_ACC_RDWR, H5P_DEFAULT);
grp = H5Gopen2(file, "Data", H5P_DEFAULT);
/*
* Access "Compressed_Data" dataset in the group.
*/
dataset = H5Dopen2(grp, "Compressed_Data", H5P_DEFAULT);
if (dataset < 0)
printf(" Dataset 'Compressed-Data' is not found. \n");
printf("\"/Data/Compressed_Data\" dataset is open \n");
/*
* Close the dataset.
*/
status = H5Dclose(dataset);
/*
* Create hard link to the Data group.
*/
status = H5Lcreate_hard(file, "Data", H5L_SAME_LOC, "Data_new", H5P_DEFAULT, H5P_DEFAULT);
/*
* We can access "Compressed_Data" dataset using created
* hard link "Data_new".
*/
dataset = H5Dopen2(file, "/Data_new/Compressed_Data", H5P_DEFAULT);
if (dataset < 0)
printf(" Dataset is not found. \n");
printf("\"/Data_new/Compressed_Data\" dataset is open \n");
/*
* Close the dataset.
*/
status = H5Dclose(dataset);
/*
* Use iterator to see the names of the objects in the root group.
*/
idx_f = H5Literate2(file, H5_INDEX_NAME, H5_ITER_INC, NULL, file_info, NULL);
/*
* Unlink name "Data" and use iterator to see the names
* of the objects in the file root direvtory.
*/
if (H5Ldelete(file, "Data", H5P_DEFAULT) < 0)
printf(" H5Ldelete failed \n");
else
printf("\"Data\" is unlinked \n");
idx_f = H5Literate2(file, H5_INDEX_NAME, H5_ITER_INC, NULL, file_info, NULL);
/*
* Use iterator to see the names of the objects in the group
* /Data_new.
*/
idx_g = H5Literate_by_name2(grp, "/Data_new", H5_INDEX_NAME, H5_ITER_INC, NULL, group_info, NULL,
H5P_DEFAULT);
/*
* Close the file.
*/
H5Gclose(grp);
H5Fclose(file);
return 0;
}
/*
* Operator function.
*/
static herr_t
file_info(hid_t loc_id, const char *name, const H5L_info2_t *linfo, void *opdata)
{
/* avoid compiler warnings */
loc_id = loc_id;
opdata = opdata;
linfo = linfo;
/*
* Display group name. The name is passed to the function by
* the Library. Some magic :-)
*/
printf("\nName : %s\n", name);
return 0;
}
/*
* Operator function.
*/
static herr_t
group_info(hid_t loc_id, const char *name, const H5L_info2_t *linfo, void *opdata)
{
hid_t did; /* dataset identifier */
hid_t tid; /* datatype identifier */
H5T_class_t t_class;
hid_t pid; /* data_property identifier */
hsize_t chunk_dims_out[2];
int rank_chunk;
/* avoid warnings */
opdata = opdata;
linfo = linfo;
/*
* Open the datasets using their names.
*/
did = H5Dopen2(loc_id, name, H5P_DEFAULT);
/*
* Display dataset name.
*/
printf("\nName : %s\n", name);
/*
* Display dataset information.
*/
tid = H5Dget_type(did); /* get datatype*/
pid = H5Dget_create_plist(did); /* get creation property list */
/*
* Check if dataset is chunked.
*/
if (H5D_CHUNKED == H5Pget_layout(pid)) {
/*
* get chunking information: rank and dimensions.
*/
rank_chunk = H5Pget_chunk(pid, 2, chunk_dims_out);
printf("chunk rank %d, dimensions %lu x %lu\n", rank_chunk, (unsigned long)(chunk_dims_out[0]),
(unsigned long)(chunk_dims_out[1]));
}
else {
t_class = H5Tget_class(tid);
if (t_class < 0) {
puts(" Invalid datatype.\n");
}
else {
if (t_class == H5T_INTEGER)
puts(" Datatype is 'H5T_NATIVE_INTEGER'.\n");
if (t_class == H5T_FLOAT)
puts(" Datatype is 'H5T_NATIVE_FLOAT'.\n");
if (t_class == H5T_STRING)
puts(" Datatype is 'H5T_NATIVE_STRING'.\n");
if (t_class == H5T_BITFIELD)
puts(" Datatype is 'H5T_NATIVE_BITFIELD'.\n");
if (t_class == H5T_OPAQUE)
puts(" Datatype is 'H5T_NATIVE_OPAQUE'.\n");
if (t_class == H5T_COMPOUND)
puts(" Datatype is 'H5T_NATIVE_COMPOUND'.\n");
}
}
H5Dclose(did);
H5Pclose(pid);
H5Tclose(tid);
return 0;
}
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