ENH: Series.sort_index perf enhancement

Author: wesm

bench/zoo_bench.R

@@ -1,13 +1,21 @@
 library(zoo)
+library(xts)
 
 indices = rep(NA, 100000)
 for (i in 1:100000)
   indices[i] <- paste(sample(letters, 10), collapse="")
 
 timings <- numeric()
 
-x <- zoo(rnorm(100000), indices)
-y <- zoo(rnorm(90000), indices[sample(1:100000, 90000)])
+## x <- zoo(rnorm(100000), indices)
+## y <- zoo(rnorm(90000), indices[sample(1:100000, 90000)])
+
+## indices <- as.POSIXct(1:100000)
+
+indices <- as.POSIXct(Sys.Date()) + 1:100000
+
+x <- xts(rnorm(100000), indices)
+y <- xts(rnorm(90000), indices[sample(1:100000, 90000)])
 
 for (i in 1:10) {
   gc()

pandas/core/index.py

@@ -257,15 +257,14 @@ def union(self, other):
             if len(indexer) > 0:
                 other_diff = other.values.take(indexer)
                 result = list(self) + list(other_diff)
+                # timsort wins
+                try:
+                    result.sort()
+                except Exception:
+                    pass
             else:
                 # contained in
-                result = list(self)
-
-            # timsort wins
-            try:
-                result.sort()
-            except Exception:
-                pass
+                result = sorted(self)
 
         # for subclasses
         return self._wrap_union_result(other, result)

pandas/core/series.py

@@ -1057,7 +1057,8 @@ def sort_index(self, ascending=True):
         if not ascending:
             sort_index = sort_index[::-1]
         new_labels = labels.take(sort_index)
-        return self.reindex(new_labels)
+        new_values = self.values.take(sort_index)
+        return Series(new_values, new_labels)
 
     def argsort(self, axis=0, kind='quicksort', order=None):
         """