Updating columns by group
You often need to create new intermediate columns to get to the final result but don't necessarily need these intermediate columns in the final result. This is a very common pattern in data analysis.
In this exercise, you will work with a new data.table, batrips_new, which is almost identical to batrips, except we randomly introduced some missing values in the duration column.
Questo esercizio fa parte del corso
Data Manipulation with data.table in R
Esercizio pratico interattivo
Prova a risolvere questo esercizio completando il codice di esempio.
# Calculate the mean duration for each month
batrips_new[, ___,
by = month(start_date)]