regex - Remove first "." from values in R

Question

I have a dataset with different values in R. Some values are like 11.474 and others like 1.034.496 in the same column. I would like to change the values with two dots from 1.034.496 to 1034.496. Is there anyone who could help me please?

Thanks for the help!

question from:https://stackoverflow.com/questions/66048544/remove-first-from-values-in-r

Answer 1

Use gsub with Perl regexes:

df <- data.frame(a = c('11.474', '1.034.496', '1.234.034.496'))
df$a = gsub('[.](?=.*[.])', '', df$a, perl = TRUE)
print(df)
##             a
## 1      11.474
## 2    1034.496
## 3 1234034.496

Here, [.](?=.*[.]) is a literal dot (has to be escaped like so . or put into a character class like so: [.]), followed by a literal dot using positive lookahead: (?=PATTERN).