Using summarise() and group_by() in RStudio


#1

Hello! I am following along in an online textbook on how to use summarise / group_by. I came across the following from the nycflights13 data package:

by_day <- group_by(flights, year, month, day)
summarise(by_day, delay = mean(dep_delay, na.rm = TRUE))

In the textbook, it should yield the following:

#> Source: local data frame [365 x 4]_
#> Groups: year, month [?]_
#> _
#> year month day delay_
#> _
#> 1 2013 1 1 11.55_
#> 2 2013 1 2 13.86_
#> 3 2013 1 3 10.99_
#> 4 2013 1 4 8.95_
#> 5 2013 1 5 5.73_
#> 6 2013 1 6 7.15_
#> # … with 359 more rows_

Instead, I get this…

delay
1 12.63907

Further on in the textbook, I came across the following using the same nycflights13 data package:

by_dest <- group_by(flights, dest)
delay <- summarise(by_dest,
count = n(),
dist = mean(distance, na.rm = TRUE),
delay = mean(arr_delay, na.rm = TRUE)
)
delay <- filter(delay, count > 20, dest != “HNL”)

In the console, I get this…

by_dest <- group_by(flights, dest)

delay <- summarize(by_dest,

  • count = n(),
  • dist = mean(distance, na.rm = TRUE),
  • delay = mean(arr_delay, na.rm = TRUE)
  • )
    Error: This function should not be called directly

delay <- filter(delay, count > 20, dest != “HNL”)
Error in filter(delay, count > 20, dest != “HNL”) :
object ‘delay’ not found

I updated all my packages but I cannot get past this point in the online book! I would appreciate any assistance and thank you in advance.
–G


#2

Something messed up with your libraries? Restart R, reload dplyr, repeat?


#3

That worked exactly as you said! Much appreciated.