Yes, there is support for writing VL strings in datasets, but not in
attributes. Also there is no support for writing VL non-strings for datasets
or attributes. There is an existing issue (JAVA-1833) in our bug database for
these issues and I will add this request for attribute support.
Allen
On Wednesday, April 16, 2014 12:06:41 PM Daniel Tetlow wrote:
> Hi,
>
> I've seen the Java example for variable length string datasets, but I just
> want to write some attributes. What I'm trying to do is create files with
> UTF8 string attributes that can be easily read by h5py. But the only way
> h5py will work with UTF8 attributes is if they're variable length.
>
> The code below works fine for a fixed length attribute, but crashes the JVM
> when I set the dtype size to H5T_VARIABLE.
>
> import java.io.File;
> import static ncsa.hdf.hdf5lib.H5.*;
> import static ncsa.hdf.hdf5lib.HDF5Constants.*;
> import org.apache.log4j.BasicConfigurator;
>
> public class WriteVariableUTF8 {
>
> public static void main(String[] args) throws Exception {
> BasicConfigurator.configure(); // log4j.
>
> byte[] bytes = "world".getBytes("UTF-8");
>
> File path = new File("C:/Users/dan/variableutf8.h5");
> int file = H5Fcreate(path.getAbsolutePath(), H5F_ACC_TRUNC,
> H5P_DEFAULT, H5P_DEFAULT);
>
> int dtype = H5Tcopy(H5T_C_S1);
> H5Tset_cset(dtype, H5T_CSET_UTF8);
> H5Tset_size(dtype, H5T_VARIABLE); // works if I set size to
> bytes.length. H5Tset_strpad(dtype, H5T_STR_NULLTERM);
>
> int space = H5Screate(H5S_SCALAR);
> int attr = H5Acreate(file, "hello", dtype, space, H5P_DEFAULT,
> H5P_DEFAULT); H5Awrite(attr, dtype, bytes);
>
> H5Aclose(attr);
> H5Sclose(space);
> H5Fclose(file);
> }
> }
>
>
> Thanks for your help,
>
> Dan Tetlow
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