Change Variable Name using Regular Expression-CodePudding

I would appreciate your help.

I want to change variables' name in R. The name of variables is "CACRAGE", "CACRAA1", etc. I want to remove "AC" in the middle, changing variables' name to "CRAGE", "CCRAA1". I've tried the following expression and it does not work. Please help me!

gsub(pattern = '^CAC([A-Z]{3,}', replacement = '^C([A-Z]{3,}', colnames(milwaukee_test), fixed = TRUE)

Thank you.

CodePudding user response：

Why not just replace "CAC" with "C" if it occurs at the beginning of the name?

milwaukee_test <- data.frame(CACRAGE = 1:3, CACRAA1 = 2:4)

names(milwaukee_test) <- sub(pattern = '^CAC', "C", colnames(milwaukee_test))

milwaukee_test
#>   CRAGE CRAA1
#> 1     1     2
#> 2     2     3
#> 3     3     4

^{Created on 2022-08-20 with reprex v2.0.2}

CodePudding user response：

You can use

gsub(pattern = '^CAC(?=[A-Z]{3})', replacement = 'C', colnames(milwaukee_test), perl = TRUE)

Note

You need perl = TRUE, not fixed = TRUE, in order to use regex and lookarounds in it
^CAC(?=[A-Z]{3}) matches CAC at the start of string that is immediately followed with three uppercase ASCII letters.