Is there a way to create a new column based on the values of another one using dplyr in R?

Question

I have been using base R but I want to use dplyr. This is what I have been doing:

data$newvariable <- 0
data$newvariable[data$oldvariable=="happy"] <- "good"
data$newvariable[data$oldvariable=="unhappy"] <- "bad"
data$newvariable[data$oldvariable=="depressed"] <- "super_bad"

Answer 1

In dplyr, we can use case_when to assign new values to newvariable based on oldvariable.

library(dplyr)

data = data.frame(
  oldvariable = c("happy", "unhappy", "depressed")
)

data %>%
  mutate(newvariable = case_when(
    oldvariable == "happy" ~ "good",
    oldvariable == "unhappy" ~ "bad",
    oldvariable == "depressed" ~ "super_bad"
  ))
#>   oldvariable newvariable
#> 1       happy        good
#> 2     unhappy         bad
#> 3   depressed   super_bad