Get random subsample from pyfits data table

I have a very simple question, but Google does not seem to be able to help me here. I want a subsample of a pyfits table... basically just remove 90% of the rows, or something like that. I read the table with:

data_table = pyfits.getdata(base_dir + filename)

I like the pyfits table organization where I access a field with data_table.field(fieldname), so I would like to keep the data structure, but remove rows.