Combining i, j, and by (II)
As you did in the last chapter, you will combine the i, j, and by arguments, but this time modify the existing data.table by reference in j.
Diese Übung ist Teil des Kurses
Data Manipulation with data.table in R
Anleitung zur Übung
For all rows where duration is greater than 600, group batrips by start_station and end_station to add a new column (mean_duration) by reference which calculates the mean duration of all trips.
Interaktive Übung
Vervollständige den Beispielcode, um diese Übung erfolgreich abzuschließen.
# Add the mean_duration column
___