revcode allows you to reverse code a numeric variable. If, say,
you have a Likert item that has values of 1, 2, 3, 4, and 5, the function inverts
the scale so that 1 = 5, 2 = 4, 3 = 3, 4 = 2, and 5 = 1.
Value
The function returns a numeric vector that reverse codes the the numeric vector that was supplied to it.
Details
This function passes over NAs you may have in your variable. It does assume, reasonably might I add, that the observed values include both the minimum and the maximum. This is usually the case in a discrete ordered-categorical variable (like a Likert item). It also assumes that the numeric vector supplied to it contains all possible values and that the minimum observed value is 1. This is usually a safe assumption in survey data where the variable of interest is ordinal (either on a 1:4 scale, or 1:5 scale, or 1:10 scale). No matter, use the function with that in mind.
Examples
data.frame(x1 = rep(c(1:7, NA), 2),
x2 = c(1:10, 1:4, NA, NA),
x3 = rep(c(1:4), 4)) -> example_data
library(dplyr)
library(magrittr)
example_data %>% mutate_at(vars("x1", "x2", "x3"), ~revcode(.))
#> x1 x2 x3
#> 1 7 10 4
#> 2 6 9 3
#> 3 5 8 2
#> 4 4 7 1
#> 5 3 6 4
#> 6 2 5 3
#> 7 1 4 2
#> 8 NA 3 1
#> 9 7 2 4
#> 10 6 1 3
#> 11 5 10 2
#> 12 4 9 1
#> 13 3 8 4
#> 14 2 7 3
#> 15 1 NA 2
#> 16 NA NA 1