Summarizing by state and region
You can group by multiple columns instead of grouping by one. Here, you'll practice aggregating by state and region, and notice how useful it is for performing multiple aggregations in a row.
counties_selected <- counties %>%
select(region, state, county, population)
Это упражнение является частью курса
Data Manipulation with dplyr
Интерактивное практическое упражнение
Попробуйте выполнить это упражнение, дополнив этот пример кода.
counties_selected %>%
# Group and summarize to find the total population
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