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air_time not airtime

This commit is contained in:
hadley 2016-09-16 14:02:42 -05:00
parent 7785b01ca2
commit 55f0e1b0e5
2 changed files with 3 additions and 3 deletions
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2
datetimes.Rmd
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@ -310,7 +310,7 @@ Setting larger components of a date to a constant is a powerful technique that a
1. Compare `dep_time`, `sched_dep_time` and `dep_delay`. Are they consistent?
Explain your findings.
1. Compare `airtime` with the duration between the departure and arrival.
1. Compare `air_time` with the duration between the departure and arrival.
Explain your findings. (Hint: consider the location of the airport.)
1. How does the average delay time change over the course of a day?

4
transform.Rmd
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@ -356,7 +356,7 @@ There are many functions for creating new variables that you can use with `mutat
* Arithmetic operators: `+`, `-`, `*`, `/`, `^`. These are all vectorised,
using the so called "recycling rules". If one parameter is shorter than
the other, it will be automatically extended to be the same length. This
is most useful when one of the arguments is a single number: `airtime / 60`,
is most useful when one of the arguments is a single number: `air_time / 60`,
`hours * 60 + minute`, etc.
Arithmetic operators are also useful in conjunction with the aggregate
@ -453,7 +453,7 @@ ggplot(flights, aes(air_time - airtime2)) + geom_histogram()
Convert them to a more convenient representation of number of minutes
since midnight.
1. Compare `airtime` with `arr_time - dep_time`. What do you expect to see?
1. Compare `air_time` with `arr_time - dep_time`. What do you expect to see?
What do you see? What do you need to do to fix it?
1. Compare `dep_time`, `sched_dep_time`, and `dep_delay`. How would you