I am using R. I have a data frame with "year , price, mileage" columns. I want to group the df by year first and then sort each group by mileage. How can I do this?
The 'dplyr' package in R is ideal for these types of data manipulation tasks. The arrange function for example can group a dataframe by a certain column, and then sort by another column. For example:
arrange(df, desc(mileage), group_by = year)