HDF4: Porting from hdfsd to hdfread

I'm having trouble porting old code from the now obsolete HDFSD to the new hdfread (MATLAB.IO.HDF4.SD)

Previously, I'd open a HDF file for input, get the number of datasets present and then read them in one by one:

sd_id = hdfsd( 'start',filepath, 'rdonly' );

[ndatasets,nglobal_attr,status] = hdfsd('fileinfo',sd_id);

for icnt=0:(ndatasets-1)

          sds_id = hdfsd( 'select', sd_id, icnt );

          <read each dataset in to a variable>
  end

Using hdfread, I can't seem to access anything but the 0th datafile. Any ideas? The documentation doesn't seem to cover this, and I can't "see" other datafiles using hdftool.

Answer 1

[Mathew Owens]

.... and of course, an extra couple of hours monkeying around and I figure it out. Just in case anyone else has a similar issue in the future, here's the solution:

sdID = sd.start(filepath,'read');
[ndatasets,ngatts] = sd.fileInfo(sdID);

for icnt=0:(ndatasets-1) 
    sdsID = sd.select(sdID,icnt);
    data=sd.readData(sdsID);  
    sd.endAccess(sdsID);
    sd.close(sdID);
end

[Minyu Xiao]

Your answer helps me a lot. Thank you.

[Piyush Ojha]

why it is showing

Undefined variable "sd" or class "sd.start".

Please help

[Mathew Owens]

Sorry, no idea. I moved over to python some time ago.