mygpo/administration/group.py

   1 from datetime import datetime
   2 from collections import defaultdict
   3
   4
   5 DEFAULT_RELEASE = datetime(1970, 1, 1)
   6 _SORT_KEY = lambda eps: eps[0].released or DEFAULT_RELEASE
   7
   8 class PodcastGrouper(object):
   9     """ Groups episodes of two podcasts based on certain features
  10
  11     The results are sorted by release timestamp """
  12
  13     DEFAULT_RELEASE = datetime(1970, 1, 1)
  14
  15     def __init__(self, podcasts):
  16
  17         if not podcasts or (None in podcasts):
  18             raise ValueError('podcasts must not be None')
  19
  20         self.podcasts = podcasts
  21
  22
  23     def __get_episodes(self):
  24         episodes = {}
  25         for podcast in self.podcasts:
  26             episodes.update(dict((e._id, e) for e in podcast.episode_set.all()))
  27
  28         return episodes
  29
  30
  31     def group(self, get_features):
  32
  33         episodes = self.__get_episodes()
  34
  35         episode_groups = defaultdict(list)
  36
  37         episode_features = map(get_features, episodes.items())
  38
  39         for features, episode_id in episode_features:
  40             episode = episodes[episode_id]
  41             episode_groups[features].append(episode)
  42
  43         groups = sorted(episode_groups.values(), key=_SORT_KEY)
  44
  45         return enumerate(groups)