MATLAB: How to read or understand this code

#reading a struct

"hinfo.GroupHierarchy.Groups(1,3).Groups(1,1).Groups(1,2).Groups,2"
Where,
  • hinfo = hdf5info(dateiname);
  • dateiname = [dateirumpf '.H5'];
  • dateirumpf is a character string.

Best Answer

It is pretty much just a way to get information from the fields. Lets do an example. I will first make a hdf file
hinfo = hdf5info('example.h5')
This results in
hinfo = 
            Filename: 'example.h5'
          LibVersion: '1.8.12'
              Offset: 0
            FileSize: 35072
      GroupHierarchy: [1x1 struct]
The first part of the code i calling the "GroupHierarchy" field
hinfo.GroupHierarchy
Which returns
        Filename: 'D:\Program Files (x86)\Matlab\toolbox\matlab\demos\example.h5'
            Name: '/'
          Groups: [1x4 struct]
        Datasets: []
       Datatypes: []
           Links: []
      Attributes: [1x2 struct]
The next part of the code is calling the Groups field with the location (1,3). This seems to return the whole row of field 3
From the command window
        Filename: 'D:\Program Files (x86)\Matlab\toolbox\matlab\demos\example.h5'
            Name: '/g3'
          Groups: []
        Datasets: [1x32 struct]
       Datatypes: []
           Links: []
      Attributes: []
As you see, the "Group" field is empty in this case and there is no reason to call it. But we are able to call Datasets
hinfo.GroupHierarchy.Groups(1,3).Datasets(1,1)
Which returns
       Filename: 'D:\Program Files (x86)\Matlab\toolbox\matlab\demos\example.h5'
            Name: '/g3/VLstring'
            Rank: 1
        Datatype: [1x1 struct]
            Dims: 2
         MaxDims: 2
          Layout: 'contiguous'
      Attributes: []
           Links: []
       Chunksize: []
       FillValue: ''
Hope this helped. I would also like to tell you that Matlab recommends that you use H5INFO instead of hdf5info.
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