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Diffstat (limited to 'HDF5Examples/C/H5T/h5ex_t_floatatt.c')
-rw-r--r-- | HDF5Examples/C/H5T/h5ex_t_floatatt.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/HDF5Examples/C/H5T/h5ex_t_floatatt.c b/HDF5Examples/C/H5T/h5ex_t_floatatt.c new file mode 100644 index 0000000..d8f9f7c --- /dev/null +++ b/HDF5Examples/C/H5T/h5ex_t_floatatt.c @@ -0,0 +1,141 @@ +/************************************************************ + + This example shows how to read and write floating point + datatypes to an attribute. The program first writes + floating point numbers to an attribute with a dataspace of + DIM0xDIM1, then closes the file. Next, it reopens the + file, reads back the data, and outputs it to the screen. + + ************************************************************/ + +#include "hdf5.h" +#include <stdio.h> +#include <stdlib.h> + +#define FILE "h5ex_t_floatatt.h5" +#define DATASET "DS1" +#define ATTRIBUTE "A1" +#define DIM0 4 +#define DIM1 7 + +int +main(void) +{ + hid_t file, space, dset, attr; /* Handles */ + herr_t status; + hsize_t dims[2] = {DIM0, DIM1}; + double wdata[DIM0][DIM1], /* Write buffer */ + **rdata; /* Read buffer */ + int ndims; + hsize_t i, j; + + /* + * Initialize data. + */ + for (i = 0; i < DIM0; i++) + for (j = 0; j < DIM1; j++) + wdata[i][j] = (double)i / (j + 0.5) + j; + ; + + /* + * Create a new file using the default properties. + */ + file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT); + + /* + * Create dataset with a null dataspace. + */ + space = H5Screate(H5S_NULL); + dset = H5Dcreate(file, DATASET, H5T_STD_I32LE, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT); + status = H5Sclose(space); + + /* + * Create dataspace. Setting maximum size to NULL sets the maximum + * size to be the current size. + */ + space = H5Screate_simple(2, dims, NULL); + + /* + * Create the attribute and write the floating point data to it. + * In this example we will save the data as 64 bit little endian + * IEEE floating point numbers, regardless of the native type. The + * HDF5 library automatically converts between different floating + * point types. + */ + attr = H5Acreate(dset, ATTRIBUTE, H5T_IEEE_F64LE, space, H5P_DEFAULT, H5P_DEFAULT); + status = H5Awrite(attr, H5T_NATIVE_DOUBLE, wdata[0]); + + /* + * Close and release resources. + */ + status = H5Aclose(attr); + status = H5Dclose(dset); + status = H5Sclose(space); + status = H5Fclose(file); + + /* + * Now we begin the read section of this example. Here we assume + * the attribute has the same name and rank, but can have any size. + * Therefore we must allocate a new array to read in data using + * malloc(). + */ + + /* + * Open file, dataset, and attribute. + */ + file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT); + dset = H5Dopen(file, DATASET, H5P_DEFAULT); + attr = H5Aopen(dset, ATTRIBUTE, H5P_DEFAULT); + + /* + * Get dataspace and allocate memory for read buffer. This is a + * two dimensional attribute so the dynamic allocation must be done + * in steps. + */ + space = H5Aget_space(attr); + ndims = H5Sget_simple_extent_dims(space, dims, NULL); + + /* + * Allocate array of pointers to rows. + */ + rdata = (double **)malloc(dims[0] * sizeof(double *)); + + /* + * Allocate space for floating point data. + */ + rdata[0] = (double *)malloc(dims[0] * dims[1] * sizeof(double)); + + /* + * Set the rest of the pointers to rows to the correct addresses. + */ + for (i = 1; i < dims[0]; i++) + rdata[i] = rdata[0] + i * dims[1]; + + /* + * Read the data. + */ + status = H5Aread(attr, H5T_NATIVE_DOUBLE, rdata[0]); + + /* + * Output the data to the screen. + */ + printf("%s:\n", ATTRIBUTE); + for (i = 0; i < dims[0]; i++) { + printf(" ["); + for (j = 0; j < dims[1]; j++) + printf(" %6.4f", rdata[i][j]); + printf("]\n"); + } + + /* + * Close and release resources. + */ + free(rdata[0]); + free(rdata); + status = H5Aclose(attr); + status = H5Dclose(dset); + status = H5Sclose(space); + status = H5Fclose(file); + + return 0; +} |