From 7472e114bfdac192cf2585a286376e5e0e07013b Mon Sep 17 00:00:00 2001
From: "David X. Lau" <liuslevis@users.noreply.github.com>
Date: Fri, 6 Apr 2018 22:38:33 +0800
Subject: [PATCH] fix type error caused by: df[mask] = 0

When `mask` is all `False`, pandas will raise TypeError: Cannot do inplace boolean setting on mixed-types with a non np.nan value.

Reproduce when import csvdir_equities from a .csv file, like below:

```
date,time,close,high,low,match,open,volume,turnover,matchitems
2018/04/04,2018/4/04,172.07,172.41,166.13,172.07,166.88,24573593,0,0
2018/04/05,2018/4/05,172.57,176.56,171.17,172.57,175.48,18250947,0,0
---
 zipline/data/us_equity_pricing.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/zipline/data/us_equity_pricing.py b/zipline/data/us_equity_pricing.py
index 0cfdd700a5..b21210e8a1 100644
--- a/zipline/data/us_equity_pricing.py
+++ b/zipline/data/us_equity_pricing.py
@@ -160,7 +160,7 @@ def winsorise_uint32(df, invalid_data_behavior, column, *columns):
                 stacklevel=3,  # one extra frame for `expect_element`
             )
 
-    df[mask] = 0
+    df = df.where(~mask, other=0)
     return df