course/r4ds
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

air_time not airtime

Browse Source
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
Download Patch File Download Diff File Expand all files Collapse all files

4
transform.Rmd
View File

@@ -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