mygpo/data/podcast.py

   1 #
   2 # This file is part of my.gpodder.org.
   3 #
   4 # my.gpodder.org is free software: you can redistribute it and/or modify it
   5 # under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or (at your
   7 # option) any later version.
   8 #
   9 # my.gpodder.org is distributed in the hope that it will be useful, but
  10 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11 # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
  12 # License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with my.gpodder.org. If not, see <http://www.gnu.org/licenses/>.
  16 #
  17
  18 from django.contrib.auth.models import User
  19 from mygpo.api.models import Episode, Subscription
  20 from mygpo.data.models import PodcastTag
  21
  22 def avg_update_interval(podcast):
  23     """
  24     returns the average interval between episodes for a given podcast
  25     """
  26     unique_timestamps = Episode.objects.filter(podcast=p, timestamp__isnull=False).order_by('timestamp').values('timestamp').distinct()
  27     c = unique_timestamps.count()
  28     t1 = unique_timestamps[0]['timestamp']
  29     t2 = unique_timestamps[c-1]['timestamp']
  30     return max(1, (t2 - t1).days / c)
  31
  32
  33 def calc_similar_podcasts(podcast):
  34     """
  35     calculates and returns a list of podcasts that seem to be similar
  36     to the given one.
  37
  38     Probably an expensive operation
  39     """
  40     tags = [t.tag for t in PodcastTag.objects.filter(podcast=podcast).only('tag').distinct()]
  41     users = User.objects.filter(subscription__podcast=podcast).only('id').distinct()
  42     subscribed = Subscription.objects.filter(user__in=users).only('podcast')
  43     podcast_list = {}
  44     for s in subscribed:
  45         if s.podcast == podcast:
  46             continue
  47         podcast_list[s.podcast] = podcast_list.get(s.podcast, 0) + 1
  48
  49     for p in podcast_list.iterkeys():
  50         ps_tags = [t.tag for t in PodcastTag.objects.filter(podcast=p).only('tag').distinct()]
  51         matching_tags = filter(lambda t: t in tags, ps_tags)
  52         podcast_list[p] = podcast_list[p] * max(len(matching_tags), 1)
  53
  54     l = list(podcast_list.iteritems())
  55     l.sort(key=lambda (p, count): count, reverse=True)
  56     return l
  57
  58