Appending more datasets into an existing Hdf5 file without deleting other groups and datasets

Question

I have an HDF5 file which contains groups and subgroups inside which there are datasets. I want to open the file and add some datasets to the groups. I took the following approach which is quite simple in python.

    import h5py
    f = h5py.File('filename.h5','w')
    f.create_dataset('/Group1/subgroup1/dataset4', data=pngfile)
    f.close()

The before file looked like this

After File looks like this

but I want it to not delete other datasets and groups but rather just append the dataset4 in the line.

Answer 1

Just like with the Python open() function, 'w' will truncate any existing file. Use the 'a' mode to add content to the file:

import h5py
f = h5py.File('filename.h5','a')
f.create_dataset('/Group1/subgroup1/dataset4', data=pngfile)
f.close()