Adding columns by group
Recall that you can perform computations by group using the by argument of the data.table. In this exercise, you will add new columns by group to the original data.table by reference.
Diese Übung ist Teil des Kurses
Data Manipulation with data.table in R
Interaktive Übung
Vervollständige den Beispielcode, um diese Übung erfolgreich abzuschließen.
# Add a new column equal to total trips for every start station
batrips[, ___, by = ___]