Merge pull request #380 from kernc/related_posts_skipcategory

Add related_posts option RELATED_POSTS_SKIP_SAME_CATEGORY

related_posts/Readme.rst

@@ -20,8 +20,15 @@ For example::
 
 
 Your related posts should share a common tag. You can also use ``related_posts:`` in your post's meta data.
-The 'related_posts:' meta data works together with your existing slugs:
+The 'related_posts:' meta data works together with your existing slugs::
 
-    related_posts: slug1,slug2,slug3...slugN 
+    related_posts: slug1, slug2, slug3, ... slugN
 
-N represents the RELATED_POSTS_MAX
+``N`` represents the ``RELATED_POSTS_MAX``.
+
+Additionally, you can specify::
+
+    RELATED_POSTS_SKIP_SAME_CATEGORY = True
+
+in your settings file. With this setting, ``article.related_posts`` will
+contain only related posts from categories other than the original article's.

related_posts/related_posts.py

@@ -7,12 +7,15 @@ Adds related_posts variable to article's context
 
 from pelican import signals
 from collections import Counter
+from itertools import chain
 
 
 def add_related_posts(generator):
     # get the max number of entries from settings
     # or fall back to default (5)
     numentries = generator.settings.get('RELATED_POSTS_MAX', 5)
+    # Skip all posts in the same category as the article
+    skipcategory = generator.settings.get('RELATED_POSTS_SKIP_SAME_CATEGORY', False)
     for article in generator.articles:
         # set priority in case of forced related posts
         if hasattr(article,'related_posts'):
@@ -22,6 +25,7 @@ def add_related_posts(generator):
             # get related articles
             for slug in related_posts:
                 i = 0
+                slug = slug.strip()
                 for a in generator.articles:
                     if i >= numentries: # break in case there are max related psots
                         break
@@ -36,12 +40,14 @@ def add_related_posts(generator):
                 continue
 
             # score = number of common tags
-            scores = Counter()
-            for tag in article.tags:
-                scores += Counter(generator.tags[tag])
+            related = chain(*(generator.tags[tag] for tag in article.tags))
+            if skipcategory:
+                related = (other for other in related
+                                 if other.category != article.category)
+            scores = Counter(related)
 
             # remove itself
-            scores.pop(article)
+            scores.pop(article, None)
 
             article.related_posts = [other for other, count 
                 in scores.most_common(numentries)]