Calculating cumulative rentals
Rolling sums smooth short-term noise, but sometimes you need the running total from the very start. Cumulative sums track how usage builds up over time, useful for capacity planning and monthly reporting.
polars is loaded as pl. The DataFrame bikes is available with columns time, rentals, and temp.
This exercise is part of the course
Data Transformation with Polars
Exercise instructions
- Add a column
cumulative_rentalswith the cumulative sum ofrentals.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Add a cumulative sum of rentals
bikes.with_columns(
pl.col("rentals").____().alias("____")
)