Move exercise to better location hadley#514

transform.Rmd

@@ -831,10 +831,6 @@ daily %>%
     effects of bad airports vs. bad carriers? Why/why not? (Hint: think about
     `flights %>% group_by(carrier, dest) %>% summarise(n())`)
 
-1.  For each plane, count the number of flights before the first delay 
-    of greater than 1 hour. (Hint: read about cummulative window functions and
-    see how their negations work, `vignette("window-functions")`)
-
 1.  What does the `sort` argument to `count()` do. When might you use it?
 
 ## Grouped mutates (and filters)
@@ -896,3 +892,6 @@ Functions that work most naturally in grouped mutates and filters are known as
     
 1.  Find all destinations that are flown by at least two carriers. Use that
     information to rank the carriers.
+
+1.  For each plane, count the number of flights before the first delay 
+    of greater than 1 hour.