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.
Cet exercice fait partie du cours
Data Manipulation with data.table in R
Instructions
- Arrange
batripsusing thestart_datecolumn in ascending order. - Group the rows by
start_station. - Extract the first and last rows of
start_date.
Exercice interactif pratique
Essayez cet exercice en complétant cet exemple de code.
# Find the first and last ride for each start_station
first_last <- batrips[___,
.(start_date = ___),
by = ___]
first_last