group_theme_sents.py

from itertools import groupby

def groupby_(obj, key=None, to_lists=True):
    sorted_ = sorted(obj, key=key)
    grouped = groupby(sorted_, key)
    if to_lists:
        grouped = {k: list(g) for k, g in grouped}
    return grouped
  
  unique_theme_key = lambda mapping: (mapping['theme']['name']), mapping['theme']['group'])
  grouped = groupby_(sent_theme_mappings, key=unique_theme_key)
  
  for theme_key, group in grouped.items():
    # theme_key: (name, group)
    # group: list of mappings corresponding to theme