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hdf5/examples/h5_attribute.c

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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 illustrates the usage of the H5A Interface functions.
* It creates and writes a dataset, and then creates and writes array,
* scalar, and string attributes of the dataset.
* Program reopens the file, attaches to the scalar attribute using
* attribute name and reads and displays its value. Then index of the
* third attribute is used to read and display attribute values.
* The H5Aiterate function is used to iterate through the dataset attributes,
* and display their names. The function is also reads and displays the values
* of the array attribute.
*/
#include <stdlib.h>
#include "hdf5.h"
#define H5FILE_NAME "Attributes.h5"
#define RANK 1 /* Rank and size of the dataset */
#define SIZE 7
#define ARANK 2 /* Rank and dimension sizes of the first dataset attribute */
#define ADIM1 2
#define ADIM2 3
#define ANAME "Float attribute" /* Name of the array attribute */
#define ANAMES "Character attribute" /* Name of the string attribute */
static herr_t attr_info(hid_t loc_id, const char *name, const H5A_info_t *ainfo, void *opdata);
/* Operator function */
int
main (void)
{
hid_t file, dataset; /* File and dataset identifiers */
hid_t fid; /* Dataspace identifier */
hid_t attr1, attr2, attr3; /* Attribute identifiers */
hid_t attr;
hid_t aid1, aid2, aid3; /* Attribute dataspace identifiers */
hid_t atype, atype_mem; /* Attribute type */
H5T_class_t type_class;
hsize_t fdim[] = {SIZE};
hsize_t adim[] = {ADIM1, ADIM2}; /* Dimensions of the first attribute */
float matrix[ADIM1][ADIM2]; /* Attribute data */
herr_t ret; /* Return value */
H5O_info_t oinfo; /* Object info */
unsigned i, j; /* Counters */
char string_out[80]; /* Buffer to read string attribute back */
int point_out; /* Buffer to read scalar attribute back */
/*
* Data initialization.
*/
int vector[] = {1, 2, 3, 4, 5, 6, 7}; /* Dataset data */
int point = 1; /* Value of the scalar attribute */
char string[] = "ABCD"; /* Value of the string attribute */
for (i=0; i < ADIM1; i++) { /* Values of the array attribute */
for (j=0; j < ADIM2; j++)
matrix[i][j] = -1.;
}
/*
* Create a file.
*/
file = H5Fcreate(H5FILE_NAME, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create the dataspace for the dataset in the file.
*/
fid = H5Screate(H5S_SIMPLE);
ret = H5Sset_extent_simple(fid, RANK, fdim, NULL);
/*
* Create the dataset in the file.
*/
dataset = H5Dcreate2(file, "Dataset", H5T_NATIVE_INT, fid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
/*
* Write data to the dataset.
*/
ret = H5Dwrite(dataset, H5T_NATIVE_INT, H5S_ALL , H5S_ALL, H5P_DEFAULT, vector);
/*
* Create dataspace for the first attribute.
*/
aid1 = H5Screate(H5S_SIMPLE);
ret = H5Sset_extent_simple(aid1, ARANK, adim, NULL);
/*
* Create array attribute.
*/
attr1 = H5Acreate2(dataset, ANAME, H5T_NATIVE_FLOAT, aid1, H5P_DEFAULT, H5P_DEFAULT);
/*
* Write array attribute.
*/
ret = H5Awrite(attr1, H5T_NATIVE_FLOAT, matrix);
/*
* Create scalar attribute.
*/
aid2 = H5Screate(H5S_SCALAR);
attr2 = H5Acreate2(dataset, "Integer attribute", H5T_NATIVE_INT, aid2,
H5P_DEFAULT, H5P_DEFAULT);
/*
* Write scalar attribute.
*/
ret = H5Awrite(attr2, H5T_NATIVE_INT, &point);
/*
* Create string attribute.
*/
aid3 = H5Screate(H5S_SCALAR);
atype = H5Tcopy(H5T_C_S1);
H5Tset_size(atype, 5);
H5Tset_strpad(atype,H5T_STR_NULLTERM);
attr3 = H5Acreate2(dataset, ANAMES, atype, aid3, H5P_DEFAULT, H5P_DEFAULT);
/*
* Write string attribute.
*/
ret = H5Awrite(attr3, atype, string);
/*
* Close attribute and file dataspaces, and datatype.
*/
ret = H5Sclose(aid1);
ret = H5Sclose(aid2);
ret = H5Sclose(aid3);
ret = H5Sclose(fid);
ret = H5Tclose(atype);
/*
* Close the attributes.
*/
ret = H5Aclose(attr1);
ret = H5Aclose(attr2);
ret = H5Aclose(attr3);
/*
* Close the dataset.
*/
ret = H5Dclose(dataset);
/*
* Close the file.
*/
ret = H5Fclose(file);
/*
* Reopen the file.
*/
file = H5Fopen(H5FILE_NAME, H5F_ACC_RDONLY, H5P_DEFAULT);
/*
* Open the dataset.
*/
dataset = H5Dopen2(file, "Dataset", H5P_DEFAULT);
/*
* Attach to the scalar attribute using attribute name, then read and
* display its value.
*/
attr = H5Aopen(dataset, "Integer attribute", H5P_DEFAULT);
ret = H5Aread(attr, H5T_NATIVE_INT, &point_out);
printf("The value of the attribute \"Integer attribute\" is %d \n", point_out);
ret = H5Aclose(attr);
/*
* Find string attribute by iterating through all attributes
*/
ret = H5Oget_info2(dataset, &oinfo, H5O_INFO_ALL);
for(i = 0; i < (unsigned)oinfo.num_attrs; i++) {
attr = H5Aopen_by_idx(dataset, ".", H5_INDEX_CRT_ORDER, H5_ITER_INC, (hsize_t)i, H5P_DEFAULT, H5P_DEFAULT);
atype = H5Aget_type(attr);
type_class = H5Tget_class(atype);
if (type_class == H5T_STRING) {
atype_mem = H5Tget_native_type(atype, H5T_DIR_ASCEND);
ret = H5Aread(attr, atype_mem, string_out);
printf("Found string attribute; its index is %d , value = %s \n", i, string_out);
ret = H5Tclose(atype_mem);
}
ret = H5Aclose(attr);
ret = H5Tclose(atype);
}
/*
* Get attribute info using iteration function.
*/
ret = H5Aiterate2(dataset, H5_INDEX_NAME, H5_ITER_INC, NULL, attr_info, NULL);
/*
* Close the dataset and the file.
*/
H5Dclose(dataset);
H5Fclose(file);
return 0;
}
/*
* Operator function.
*/
static herr_t
attr_info(hid_t loc_id, const char *name, const H5A_info_t *ainfo, void *opdata)
{
hid_t attr, atype, aspace; /* Attribute, datatype and dataspace identifiers */
int rank;
hsize_t sdim[64];
herr_t ret;
int i;
size_t npoints; /* Number of elements in the array attribute. */
float *float_array; /* Pointer to the array attribute. */
/* avoid warnings */
opdata = opdata;
/*
* Open the attribute using its name.
*/
attr = H5Aopen(loc_id, name, H5P_DEFAULT);
/*
* Display attribute name.
*/
printf("\nName : %s\n", name);
/*
* Get attribute datatype, dataspace, rank, and dimensions.
*/
atype = H5Aget_type(attr);
aspace = H5Aget_space(attr);
rank = H5Sget_simple_extent_ndims(aspace);
ret = H5Sget_simple_extent_dims(aspace, sdim, NULL);
/*
* Display rank and dimension sizes for the array attribute.
*/
if(rank > 0) {
printf("Rank : %d \n", rank);
printf("Dimension sizes : ");
for (i=0; i< rank; i++)
printf("%d ", (int)sdim[i]);
printf("\n");
}
/*
* Read array attribute and display its type and values.
*/
if (H5T_FLOAT == H5Tget_class(atype)) {
printf("Type : FLOAT \n");
npoints = H5Sget_simple_extent_npoints(aspace);
float_array = (float *)malloc(sizeof(float)*(int)npoints);
ret = H5Aread(attr, atype, float_array);
printf("Values : ");
for( i = 0; i < (int)npoints; i++)
printf("%f ", float_array[i]);
printf("\n");
free(float_array);
}
/*
* Release all identifiers.
*/
H5Tclose(atype);
H5Sclose(aspace);
H5Aclose(attr);
return 0;
}
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