if_else-case_when-case_match.R

library(tidyverse)
library(gapminder)

# ifelse() will happily work and coerce your numbers into text
gapminder1 <- gapminder |> 
  mutate(life_cat = ifelse(lifeExp > 75, "High", lifeExp))

# if_else() will yell at you
gapminder1 <- gapminder |> 
  mutate(life_cat = if_else(lifeExp > 75, "High", lifeExp))

# Nested ifelses() are gross
gapminder2 <- gapminder |> 
  mutate(is_africa_europe = if_else(continent == "Africa", "Africa", if_else(continent == "Europe", "Europe", "Not Africa or Europe")))

# case_when() lets you use multiple conditions
# For catch-all conditions, you can either specify a TRUE condition at the end
# (since it'll be the last-checked condition):
gapminder3 <- gapminder |> 
  mutate(is_africa_europe = case_when(
    continent == "Africa" ~ "Africa",
    continent == "Europe" ~ "Europe",
    TRUE ~ "Not Africa or Europe"
  ))

# Or you can use the .default argument:
gapminder3 <- gapminder |> 
  mutate(is_africa_europe = case_when(
    continent == "Africa" ~ "Africa",
    continent == "Europe" ~ "Europe",
    .default = "Not Africa or Europe"
  ))

# To recode values in a specific column, you can use a simplified version of
# case_when() called case_match()
gapminder4 <- gapminder |> 
  # Change specific categories
  mutate(continent_different = case_match(continent,
    "Africa" ~ "The African Continent",
    .default = continent
  )) |> 
  # Collapse categories
  mutate(collapsed = case_match(continent,
    c("Africa", "Asia") ~ "Africa or Asia",
    .default = continent
  ))