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Move exercise to better location #514

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hadley 2017-05-03 08:00:32 -05:00
parent 25b1f7fb1c
commit 74a480e5d6
1 changed files with 3 additions and 4 deletions
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transform.Rmd
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@ -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.