[Checkins] SVN: zc.table/trunk/src/zc/table/column.py Speed up column sorting (helps a lot when 10k of items are involved,

[Ignas Mikalajënas]

Log message for revision 92406:
  Speed up column sorting (helps a lot when 10k of items are involved,
  especially when you have a moderately expensive getSortKey function)
  

Changed:
  U   zc.table/trunk/src/zc/table/column.py

-=-
Modified: zc.table/trunk/src/zc/table/column.py
===================================================================
--- zc.table/trunk/src/zc/table/column.py	2008-10-20 15:19:25 UTC (rev 92405)
+++ zc.table/trunk/src/zc/table/column.py	2008-10-20 15:49:38 UTC (rev 92406)
@@ -59,11 +59,13 @@
         else:
             items = list(items) # don't mutate original
         getSortKey = self.getSortKey
-        items.sort(
-            lambda a, b: multiplier*cmp(getSortKey(a, formatter), 
-                                        getSortKey(b, formatter)))
-        return items
 
+        # let's do decorate, sort, undecorate trick here to conserve time
+        tmp_items = [(getSortKey(item, formatter), item) for item in items]
+        tmp_items.sort(lambda a, b: multiplier*cmp(a[0], b[0]))
+
+        return [item for key, item in tmp_items]
+
     def sort(self, items, formatter, start, stop, sorters):
         return self._sort(items, formatter, start, stop, sorters, 1)