For this project, use the dplyr library and pipes.
1. Since sharing projects does not work on our server, you do not have to put this exerciseinto a project. Submit just the R markdown file.
2. Open a new R markdown file in the project called exercise07.Rmd
3. Load the nycflights13 dataset
4. Compare dep_time, sched_dep_time, and dep_delay. How would you expect those three numbers to be related?
5. Brainstorm as many ways as possible to select dep_time, dep_delay, arr_time, and arr_delay from flights.
6. What happens if you specify the name of the same variable multiple times in a select() call?
7. What does the any_of() function do? Why might it be helpful in conjunction with this vector?
variables <- c("year", "month", "day", "dep_delay", "arr_delay")
8. Does the result of running the following code surprise you? How do the select helpers deal with upper and lower case by default? How can you change that default?
flights |> select(contains("TIME"))
9. Rename air_time to air_time_min to indicate units of measurement and move it to the beginning of the data frame.
10. Why doesn’t the following work, and what does the error mean?
flights |>
select(tailnum) |> arrange(arr_delay)
#> Error in ‘arrange()‘:
#> i In argument: ‘..1 = arr_delay‘.
#> Caused by error:
#> ! object ’arr_delay’ not found
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