From fd9a3f57f7ed962b49f919911410b7f7520ca523 Mon Sep 17 00:00:00 2001
From: hadley <h.wickham@gmail.com>
Date: Mon, 3 Oct 2016 16:55:56 -0500
Subject: [PATCH] Fix think-o in exercise

---
 transform.Rmd | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/transform.Rmd b/transform.Rmd
index efaa7c9..8c721f0 100644
--- a/transform.Rmd
+++ b/transform.Rmd
@@ -818,7 +818,7 @@ daily %>%
     `not_cancelled %>% count(tailnum, wt = distance)` (without using 
     `count()`).
 
-1.  Our definition of cancelled flights (`!is.na(dep_delay) & !is.na(arr_delay)`
+1.  Our definition of cancelled flights (`is.na(dep_delay) | is.na(arr_delay)`
     ) is slightly suboptimal. Why? Which is the most important column?
 
 1.  Look at the number of cancelled flights per day. Is there a pattern?