Expecting mapped output

When you know that the output of your mapped function is an expected type (here it is a numeric vector) you can leverage the map_*() family of functions to explicitly try to return that object type instead of a list.

Here you will again calculate the mean population of each country, but instead, you will use map_dbl() to explicitly append the numeric vector returned by mean() to your data frame.

This exercise is part of the course

Machine Learning in the Tidyverse

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Exercise instructions

Generate the pop_mean data frame using the map_dbl() function to calculate the population mean for each nested data frame.
Explore the pop_mean data frame using head().

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

# Calculate mean population and store result as a double
pop_mean <- gap_nested %>%
  mutate(mean_pop = map_dbl(___, ~mean(.x$___)))

# Take a look at pop_mean
head(___)

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