Computing in j (III)
In the previous exercise, you were able to pass expressions in j that returned a vector. Recall that if you want to return a data.table instead, wrap the expression with list() (or it's alias, .()). This lets you:
- Rename the column result
- Compute more than one expression on a column
- Compute on more than one column
Deze oefening maakt deel uit van de cursus
Data Manipulation with data.table in R
Praktische interactieve oefening
Probeer deze oefening eens door deze voorbeeldcode in te vullen.
# Calculate the average duration as mean_durn
mean_duration <- ___
mean_duration