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.
This exercise is part of the course
Data Manipulation with data.table in R
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Calculate the mean duration for each month
batrips_new[, ___,
by = month(start_date)]