Grouping and summarizing

Question 1

Which function turns many observations into one data point?

Answer 1

summarize()

Ex: my_tibble %>%
summarize(meanLifeExp =
mean(lifeExp))

Question 2

How can you summarize multiple things at the same time?

Answer 2

Using commas.

Ex: my_tibble %>%
summarize(meanLifeExp =
mean(lifeExp),
medianPop = median(pop))

Question 3

Which function tells dplyr to summarize within groups rather than summarizing the entire data set?

Answer 3

group_by()

Ex: my_tibble %>%
group_by(year) %>%
summarize(meanLifeExp = mean(lifeExp))

Question 4

How can you group by multiple things at the same time?

Answer 4

Using commas.

Ex: my_tibble %>%
group_by(year, continent) %>%
summarize(meanLifeExp =
mean(lifeExp),
medianPop = median(pop))

Question 5

Which function allows you to specify where the x or y axis’ should begin or end?

Answer 5

expand_limits()

Ex: … geom_point() +
expand_limits(y = 0)