Combining i, j, and by (I)
In this exercise, you will combine the i, j, and by arguments to find the first and last ride for each start station. Recall that data.table first filters the rows in i, and then groups the rows using by, and finally compute the expression in j.
Latihan ini adalah bagian dari kursus
Data Manipulation with data.table in R
Petunjuk latihan
- Arrange
batripsusing thestart_datecolumn in ascending order. - Group the rows by
start_station. - Extract the first and last rows of
start_date.
Latihan interaktif praktis
Cobalah latihan ini dengan menyelesaikan kode contoh berikut.
# Find the first and last ride for each start_station
first_last <- batrips[___,
.(start_date = ___),
by = ___]
first_last