How to convert CamelCase to not.camel.case in R

Question

In R, I\'d like to convert

c(\"ThisText\", \"NextText\")

to

c(\"this.text\", \"next.text\")

This is the r

Answer 1

You can replace all capitals with themselves and a preceeding dot with gsub, change everything tolower, and the substr out the initial dot:

x <- c("ThisText", "NextText", "LongerCamelCaseText")

substr(tolower(gsub("([A-Z])","\\.\\1",x)),2,.Machine$integer.max)
[1] "this.text"              "next.text"              "longer.camel.case.text"

Answer 2

You could do this also via the snakecase package:

install.packages("snakecase")
library(snakecase)

to_snake_case(c("ThisText", "NextText"), sep_out = ".")
# [1] "this.text" "next.text"

Github link to package: https://github.com/Tazinho/snakecase

Answer 3

Not clear what the entire set of rules is here but we have assumed that

• we should lower case any upper case character after a lower case one and insert a dot between them and also
• lower case the first character of the string if succeeded by a lower case character.

To do this we can use perl regular expressions with sub and gsub:

# test data
camelCase <-  c("ThisText", "NextText", "DON'T_CHANGE")


s <- gsub("([a-z])([A-Z])", "\\1.\\L\\2", camelCase, perl = TRUE)
sub("^(.[a-z])", "\\L\\1", s, perl = TRUE) # make 1st char lower case

giving:

[1] "this.text"    "next.text"    "DON'T_CHANGE"