Casting a long table
gdp_oceania contains the population and GDP for every country in Oceania for every five years from 1990 to 2010 and is available in your workspace. Your goal is to create wide format data.tables containing the population and total GDP for each country with each year having its own column.
Это упражнение является частью курса
Joining Data with data.table in R
Интерактивное практическое упражнение
Попробуйте выполнить это упражнение, дополнив этот пример кода.
# Split the population column by year
___(gdp_oceania, formula = ___ ~ ___, value.var = "population")