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124 lines
3.8 KiB
HTML
124 lines
3.8 KiB
HTML
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<html><head><title>
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HDF5 Draft API Example Code
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</title></head><body>
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<center>
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<h1>HDF5: API Example Code</h1>
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</center>
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<P>Example programs/sections of code below:
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<dl COMPACT>
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<dt><a href="#Example1">#1</a>
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<dd>A simple example showing how to create a file.
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<dt><a href="#Example2">#2</a>
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<dd>A example showing how to create a homogenous multi-dimensional dataset.
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<dt><a href="#Example3">#3</a>
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<dd>A example showing how to read a generic dataset.
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</dl>
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<hr>
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<h2><a name="Example1">Simple Example showing how to create a file.</a></h2>
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<P>Notes:<br>
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This example creates a new HDF5 file and allows write access.
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If the file exists already, the H5F_ACC_TRUNC flag would also be necessary to
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overwrite the previous file's information.
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<P>Code:
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<code> <pre>
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hid_t file_id;
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file_id=<A HREF="H5.apiv2.html#File-Create">H5Fcreate</a>("example1.h5",H5F_ACC_EXCL,H5P_DEFAULT_TEMPLATE,H5P_DEFAULT_TEMPLATE);
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<A HREF="H5.apiv2.html#File-Close">H5Fclose</a>(file_id);
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</pre> </code>
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<hr>
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<h2><a name="Example2">Example showing how create a homogenous multi-dimensional dataset.</a></h2>
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<P>Notes:<br>
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This example creates a 4-dimensional dataset of 32-bit floating-point
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numbers, corresponding to the current Scientific Dataset functionality.
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<P>Code:
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<code> <pre>
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1 hid_t file_id; /* new file's ID */
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2 hid_t dim_id; /* new dimensionality's ID */
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3 int rank=4; /* the number of dimensions */
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4 hsize_t dims[4]={6,5,4,3}; /* the size of each dimension */
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5 hid_t dataset_id; /* new dataset's ID */
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6 float buf[6][5][4][3]; /* storage for the dataset's data */
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7 herr_t status; /* function return status */
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8
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9 file_id = H5Fcreate ("example3.h5", H5F_ACC_TRUNC, H5P_DEFAULT,
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10 H5P_DEFAULT);
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11 assert (file_id >= 0);
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12
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13 /* Create & initialize a dimensionality object */
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14 dim_id = H5Screate_simple (rank, dims);
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15 assert (dim_id >= 0);
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16
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17 /* Create & initialize the dataset object */
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18 dataset_id = H5Dcreate (file_id, "Simple Object", H5T_NATIVE_FLOAT,
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19 dim_id, H5P_DEFAULT);
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20 assert (dataset_id >= 0);
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21
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22 <initialize data array>
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23
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24 /* Write the entire dataset out */
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25 status = H5Dwrite (dataset_id, H5T_NATIVE_FLOAT, H5S_ALL, H5S_ALL,
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26 H5P_DEFAULT, buf);
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27 assert (status >= 0);
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28
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29 /* Release the IDs we've created */
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30 H5Sclose (dim_id);
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31 H5Dclose (dataset_id);
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32 H5Fclose (file_id);
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</pre> </code>
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<hr>
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<h2><a name="Example3">Example showing how read a generic dataset.</a></h2>
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<P>Notes:<br>
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This example shows how to get the information for and display a generic
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dataset.
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<P>Code:
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<code> <pre>
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1 hid_t file_id; /* file's ID */
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2 hid_t dataset_id; /* dataset's ID in memory */
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3 hid_t space_id; /* dataspace's ID in memory */
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4 uintn nelems; /* number of elements in array */
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5 double *buf; /* pointer to the dataset's data */
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6 herr_t status; /* function return value */
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7
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8 file_id = H5Fopen ("example6.h5", H5F_ACC_RDONLY, H5P_DEFAULT);
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9 assert (file_id >= 0);
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10
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11 /* Attach to a datatype object */
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12 dataset_id = H5Dopen (file_id, "dataset1");
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13 assert (dataset_id >= 0);
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14
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15 /* Get the OID for the dataspace */
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16 space_id = H5Dget_space (dataset_id);
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17 assert (space_id >= 0);
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18
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19 /* Allocate space for the data */
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20 nelems = H5Sget_npoints (space_id);
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21 buf = malloc (nelems * sizeof(double));
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22
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23 /* Read in the dataset */
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24 status = H5Dread (dataset_id, H5T_NATIVE_DOUBLE, H5S_ALL,, H5S_ALL,
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25 H5P_DEFAULT, buf);
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26 assert (status >= 0);
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27
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28 /* Release the IDs we've accessed */
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29 H5Sclose (space_id);
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30 H5Dclose (dataset_id);
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31 H5Fclose (file_id);
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</pre> </code>
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