Exercise

Mastering simple joins

Three new data.tables have been loaded into your R session containing information about the geography and population of Australia: area, capitals, and population. Your goal is to perform a sequence of joins to build a single data.table containing information about the geographical area of each Australian state and the population of its capital city, storing the final result in a new variable: australia_stats. There are three data.tables so you will need to perform two joins. First, you will join capitals and population, and then you will join the resulting data.table to the area.

Instructions 1/2

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  • Identify the key column so you can join capitals and population. Assign the column name as a string to capitals_population_key.
  • Using this key, left join population to capitals.