Creating HDF5 file: How to create a GROUP inside a GROUP?

Dear all

I'd like to create an HDF5 file ('file_ex.hdf') which should have the following structure:

>> h5disp('file_ex.hdf')
  HDF5 file_ex.hdf 
  Group '/' 
      Attributes:
          'Form':  'short'
      Group '/ds1' 
          Group '/ds1/data1' 
              Dataset 'data' 
                  Size:  1000x1200
                  Datatype:   H5T_STD_U8LE (uint8)
                  Attributes:
                      'CLASS':  'Myclass'
                      'VERSION':  7.5
          Group '/ds1/what' 
              Attributes:
                  'product':  'COMP'
                  'time':     '000009'
      Group '/what' 
              Attributes:
       'Func':  'upper'

I managed to create an HDF5 file which contains the Attribute 'Form' and the Group '/ds1' -- but I did not manage to create a Group '/ds1/data1' contained in the Group '/ds1'. How can I create such a sub-group?

Here is the code I used:

>> h5create('file_ex.hdf','/ds1/data1',[10 20])
>> mydata = rand(10,20);
>> h5write('file_ex.hdf', '/ds1/data1', mydata)
>> h5writeatt('file_ex.hdf','/','Form','short');

The file generated by this code looks like this:

>> h5disp('file_ex.hdf')  
HDF5 file_ex.hdf 
Group '/' 
    Attributes:
        'Form':  'short'
    Group '/ds1' 
        Dataset 'data1' 
            Size:  10x20
            MaxSize:  10x20
            Datatype:   H5T_IEEE_F64LE (double)
            ChunkSize:  []
            Filters:  none
            FillValue:  0.000000

Answer 1

[Jan Orwat]

Use Low-Level Functions such as H5G.create to create custom/nested groups.

Example:

>> fid = H5F.create('myfile.h5');
>> plist = 'H5P_DEFAULT';
>> gid = H5G.create(fid,'my_group',plist,plist,plist);
>> gid2 = H5G.create(fid,'my_group2',plist,plist,plist);
>> gid1 = H5G.create(gid,'my_group_nested',plist,plist,plist);
>> H5G.close(gid1);
>> H5G.close(gid2);
>> H5G.close(gid);
>> H5F.close(fid);
>> h5disp('myfile.h5')
HDF5 myfile.h5 
Group '/' 
  Group '/my_group' 
      Group '/my_group/my_group_nested' 
  Group '/my_group2'