Recode multiple values in multiple columns with new values in R

Question

I have data frame with 18 columns. Columns 2 to 13 include numeric values such as 0, 1, 2, 4 ... I want to recode them based on range into three categories:

if columns 2:13 are 0 -> 0
if columns 2:13 between 1 & 5 -> 1
else columns 2:13 >- 2.

My attempt works, but not efficient:

df[,2:13][df[,2:13] == 1 | df[,2:13] == 2 | df[,2:13] == 3 | df[,2:13] == 4 | df[,2:13] == 5] <- 1

I appreciate your help.

Answer 1

Try findInterval:

dplyr

library(dplyr)
df %>%
  mutate(
    across(2:13, ~ findInterval(., c(0, 1, 5), rightmost.closed = TRUE) - 1L)
  )

If this gets any more complex (such as non-consecutive recoded values), we might switch to case_when:

df %>%
  mutate(
    across(2:13, ~ case_when(
      . == 0           ~ 0L,
      between(., 1, 5) ~ 1L,
      TRUE             ~ 2L
    ))
  )

base R

df[,2:13] <- lapply(df[,2:13], function(z) findInterval(z, c(0, 1, 5), rightmost.closed = TRUE) - 1L)