From 58467f9b3e46262124f4f5df2ad40bc5e52178cf Mon Sep 17 00:00:00 2001
From: Eddie Hebert <ehebert@quantopian.com>
Date: Fri, 3 Jun 2016 14:07:00 -0400
Subject: [PATCH] MAINT: Only calc inverse ratio if it applies.

Avoid unneeded work by only calcultaing the inverse ratio when it
applies to the current range.
---
 zipline/data/us_equity_loader.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/zipline/data/us_equity_loader.py b/zipline/data/us_equity_loader.py
index 61043c59..2d107d4b 100644
--- a/zipline/data/us_equity_loader.py
+++ b/zipline/data/us_equity_loader.py
@@ -189,11 +189,11 @@ class USEquityHistoryLoader(with_metaclass(ABCMeta)):
             'splits', sid)
         for s in splits:
             dt = s[0]
-            if field == 'volume':
-                ratio = 1.0 / s[1]
-            else:
-                ratio = s[1]
             if start < dt <= end:
+                if field == 'volume':
+                    ratio = 1.0 / s[1]
+                else:
+                    ratio = s[1]
                 end_loc = dts.searchsorted(dt)
                 adj_loc = end_loc
                 if is_perspective_after: