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/*
* 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 FILE "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 */
herr_t attr_info(hid_t loc_id, const char *name, 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; /* Attribute type */
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 */
unsigned i,j; /* Counters */
int idx; /* Attribute index */
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(FILE, 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 = H5Dcreate(file, "Dataset", H5T_NATIVE_INT, fid, 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 = H5Acreate(dataset, ANAME, H5T_NATIVE_FLOAT, aid1, H5P_DEFAULT);
/*
* Write array attribute.
*/
ret = H5Awrite(attr1, H5T_NATIVE_FLOAT, matrix);
/*
* Create scalar attribute.
*/
aid2 = H5Screate(H5S_SCALAR);
attr2 = H5Acreate(dataset, "Integer attribute", H5T_NATIVE_INT, aid2,
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, 4);
attr3 = H5Acreate(dataset, ANAMES, atype, aid3, H5P_DEFAULT);
/*
* Write string attribute.
*/
ret = H5Awrite(attr3, atype, string);
/*
* Close attribute and file dataspaces.
*/
ret = H5Sclose(aid1);
ret = H5Sclose(aid2);
ret = H5Sclose(aid3);
ret = H5Sclose(fid);
/*
* 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(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
/*
* Open the dataset.
*/
dataset = H5Dopen(file,"Dataset");
/*
* Attach to the scalar attribute using attribute name, then read and
* display its value.
*/
attr = H5Aopen_name(dataset,"Integer attribute");
ret = H5Aread(attr, H5T_NATIVE_INT, &point_out);
printf("The value of the attribute \"Integer attribute\" is %d \n", point_out);
ret = H5Aclose(attr);
/*
* Attach to the string attribute using its index, then read and display the value.
*/
attr = H5Aopen_idx(dataset, 2);
atype = H5Tcopy(H5T_C_S1);
H5Tset_size(atype, 5);
ret = H5Aread(attr, atype, string_out);
printf("The value of the attribute with the index 2 is %s \n", string_out);
ret = H5Aclose(attr);
ret = H5Tclose(atype);
/*
* Get attribute info using iteration function.
*/
idx = H5Aiterate(dataset, NULL, attr_info, NULL);
/*
* Close the dataset and the file.
*/
H5Dclose(dataset);
H5Fclose(file);
return 0;
}
/*
* Operator function.
*/
herr_t
attr_info(hid_t loc_id, const char *name, 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. */
/*
* Open the attribute using its name.
*/
attr = H5Aopen_name(loc_id, name);
/*
* Display attribute name.
*/
printf("\n");
printf("Name : ");
puts(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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