A new tool to apply Tag mapper rules to existing books in the library. To use it, go to Preferences->Toolbars and add the tool to the toolbar.

src/calibre/customize/builtins.py

@@ -847,6 +847,11 @@ class ActionQuickview(InterfaceActionBase):
     actual_plugin = 'calibre.gui2.actions.show_quickview:ShowQuickviewAction'
     description = _('Show a list of related books quickly')
 
+class ActionTagMapper(InterfaceActionBase):
+    name = 'Tag Mapper'
+    actual_plugin = 'calibre.gui2.actions.tag_mapper:TagMapAction'
+    description = _('Filter/transform the tags for books in the library')
+
 class ActionTemplateTester(InterfaceActionBase):
     name = 'Template Tester'
     actual_plugin = 'calibre.gui2.actions.show_template_tester:ShowTemplateTesterAction'
@@ -987,7 +992,7 @@ plugins += [ActionAdd, ActionFetchAnnotations, ActionGenerateCatalog,
         ActionAddToLibrary, ActionEditCollections, ActionMatchBooks, ActionChooseLibrary,
         ActionCopyToLibrary, ActionTweakEpub, ActionUnpackBook, ActionNextMatch, ActionStore,
         ActionPluginUpdater, ActionPickRandom, ActionEditToC, ActionSortBy,
-        ActionMarkBooks, ActionEmbed, ActionTemplateTester]
+        ActionMarkBooks, ActionEmbed, ActionTemplateTester, ActionTagMapper]
 
 # }}}
 

src/calibre/gui2/actions/tag_mapper.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python2
+# vim:fileencoding=utf-8
+# License: GPLv3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
+
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+from future_builtins import map
+
+from calibre.gui2 import gprefs
+from calibre.gui2.actions import InterfaceAction
+
+class TagMapAction(InterfaceAction):
+
+    name = 'Tag Mapper'
+    action_spec = (_('Tag Mapper'), 'tags.png', _('Filter/transform the tags for books in the library'), None)
+    action_type = 'current'
+
+    def genesis(self):
+        self.qaction.triggered.connect(self.start_map)
+
+    def start_map(self):
+        rows = self.gui.library_view.selectionModel().selectedRows()
+        selected = True
+        if not rows or len(rows) < 2:
+            selected = False
+            rows = xrange(self.gui.library_view.model().rowCount(None))
+        ids = set(map(self.gui.library_view.model().id, rows))
+        self.do_map(ids, selected)
+
+    def do_map(self, book_ids, selected):
+        from calibre.ebooks.metadata.tag_mapper import map_tags
+        from calibre.gui2.tag_mapper import RulesDialog
+        from calibre.gui2.device import BusyCursor
+        d = RulesDialog(self.gui)
+        d.setWindowTitle(_('Map tags for %d books in the library') % len(book_ids))
+        d.rules = gprefs.get('library-tag-mapper-ruleset', ())
+        txt = _('The changes will be applied to the <b>%d selected books</b>') if selected else _(
+            'The changes will be applied to <b>%d books in the library</b>')
+        d.edit_widget.msg_label.setText(d.edit_widget.msg_label.text() + '<p>' + txt % len(book_ids))
+        if d.exec_() != d.Accepted:
+            return
+        with BusyCursor():
+            rules = d.rules
+            gprefs.set('library-tag-mapper-ruleset', rules)
+            db = self.gui.current_db.new_api
+            tag_map = db.all_field_for('tags', book_ids)
+            changed_tag_map = {}
+            for book_id, tags in tag_map.iteritems():
+                tags = list(tags)
+                new_tags = map_tags(tags, rules)
+                if tags != new_tags:
+                    changed_tag_map[book_id] = new_tags
+            if changed_tag_map:
+                db.set_field('tags', changed_tag_map)
+                self.gui.library_view.model().refresh_ids(tuple(changed_tag_map), current_row=self.gui.library_view.currentIndex().row())

src/calibre/gui2/tag_mapper.py

@@ -178,7 +178,7 @@ class Rules(QWidget):
         QWidget.__init__(self, parent)
         self.l = l = QVBoxLayout(self)
 
-        self.la = la = QLabel(
+        self.msg_label = la = QLabel(
             '<p>' + _('You can specify rules to filter/transform tags here. Click the "Add Rule" button'
             ' below to get started. The rules will be processed in order for every tag until either a'
             ' "remove" or a "keep" rule matches.') + '<p>' + _(