Merge pull request #2211 from heylookltsme/better-genre

Proposal: Add specificity option to lastgenre plugin

beetsplug/lastgenre/__init__.py

@@ -109,6 +109,7 @@ class LastGenrePlugin(plugins.BeetsPlugin):
             'force': True,
             'auto': True,
             'separator': u', ',
+            'prefer_specific': False,
         })
 
         self.setup()
@@ -158,6 +159,24 @@ class LastGenrePlugin(plugins.BeetsPlugin):
         elif source == 'artist':
             return 'artist',
 
+    def _get_depth(self, tag):
+        """Find the depth of a tag in the genres tree.
+        """
+        depth = None
+        for key, value in enumerate(self.c14n_branches):
+            if tag in value:
+                depth = value.index(tag)
+                break
+        return depth
+
+    def _sort_by_depth(self, tags):
+        """Given a list of tags, sort the tags by their depths in the
+        genre tree.
+        """
+        depth_tag_pairs = [(self._get_depth(t), t) for t in tags]
+        depth_tag_pairs.sort(reverse=True)
+        return [p[1] for p in depth_tag_pairs]
+
     def _resolve_genres(self, tags):
         """Given a list of strings, return a genre by joining them into a
         single string and (optionally) canonicalizing each.
@@ -179,12 +198,19 @@ class LastGenrePlugin(plugins.BeetsPlugin):
                     parents = [find_parents(tag, self.c14n_branches)[-1]]
 
                 tags_all += parents
-                if len(tags_all) >= count:
+                # Stop if we have enough tags already, unless we need to find
+                # the most specific tag (instead of the most popular).
+                if (not self.config['prefer_specific'] and
+                        len(tags_all) >= count):
                     break
             tags = tags_all
 
         tags = deduplicate(tags)
 
+        # Sort the tags by specificity.
+        if self.config['prefer_specific']:
+            tags = self._sort_by_depth(tags)
+
         # c14n only adds allowed genres but we may have had forbidden genres in
         # the original tags list
         tags = [x.title() for x in tags if self._is_allowed(x)]

docs/plugins/lastgenre.rst

@@ -103,6 +103,19 @@ The plugin uses this weight to discard unpopular tags.  The default is to
 ignore tags with a weight less then 10. You can change this by setting
 the ``min_weight`` config option.
 
+Specific vs. Popular Genres
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+By default, the plugin sorts genres by popularity. However, you can use the
+``prefer_specific`` option to override this behavior and instead sort genres
+by specificity, as determined by your whitelist and canonicalization tree.
+
+For instance, say you have both ``folk`` and ``americana`` in your whitelist
+and canonicalization tree and ``americana`` is a leaf within ``folk``. If
+Last.fm returns both of those tags, lastgenre is going to use the most
+popular, which is often the most generic (in this case ``folk``). By setting
+``prefer_specific`` to true, lastgenre would use ``americana`` instead.
+
 Configuration
 -------------
 
@@ -126,6 +139,8 @@ configuration file. The available options are:
   Default: ``yes``.
 - **min_weight**: Minimum popularity factor below which genres are discarded.
   Default: 10.
+- **prefer_specific**: Sort genres by the most to least specific, rather than
+  most to least popular. Default: ``no``.
 - **source**: Which entity to look up in Last.fm. Can be
   either ``artist``, ``album`` or ``track``.
   Default: ``album``.