This is a small package that exposes a single function to make managing if-else logic in R more pleasing to look at.
library(elif)
x <- with(mtcars, elif(
mpg < 20 -> "low",
mpg < 25 -> "med", "hi"
))
This produces the following output:
> aggregate(mpg~x, mtcars, function(x) c(min=min(x), max=max(x)))
x mpg.min mpg.max
1 hi 26.0 33.9
2 low 10.4 19.7
3 med 21.0 24.4
You can also provide a vector as the final argument. Omitting a final assignment expression will fill the vector with NAs where a predicate is not matched.
y <- with(mtcars, elif(
mpg < 20 -> "low",
mpg < 25 -> "med", cyl
))
> table(y)
y
4 low med
6 18 8
elif is also dplyr friendly and provides a function alias more aligned with the
tidyverse naming convention: else_if
, although the two are functionally
identical:
library(dplyr)
mtcars <- mtcars %>%
mutate(
mpg_char = else_if(
mpg > 25 -> 'hi',
mpg < 20 -> 'lo', 'med'
),
cyl_char = else_if(
cyl == 4 -> 'four-banger',
cyl == 8 -> 'gas-guzzler', 'average'
))
> head(mtcars)
mpg cyl disp hp drat wt qsec vs am gear carb mpg_char cyl_char
1 21.0 6 160 110 3.90 2.620 16.46 0 1 4 4 med average
2 21.0 6 160 110 3.90 2.875 17.02 0 1 4 4 med average
3 22.8 4 108 93 3.85 2.320 18.61 1 1 4 1 med four-banger
4 21.4 6 258 110 3.08 3.215 19.44 1 0 3 1 med average
5 18.7 8 360 175 3.15 3.440 17.02 0 0 3 2 lo gas-guzzler
6 18.1 6 225 105 2.76 3.460 20.22 1 0 3 1 lo average