remove text after final period in string

Question

I have a grep puzzle that\'s eluding me: I\'d like to remove the text following the final period in a collection of strings (i am using R, so perl

Answer 1

You can use sub for example like this:

sub('(.*)[.](.*)','\\1',c('abc.com.foo.bar','ABCD.txt'))
[1] "abc.com.foo" "ABCD"  

Answer 2

And a non-regex answer for no reason whatsoever:

test <- c("abc.com.foo.bar","ABCD.txt")
sapply(strsplit(test,"\\."), function(x) paste0(head(x,-1),collapse=".") )
#[1] "abc.com.foo" "ABCD"

Answer 3

Here are a few solutions:

sub("^(.*)[.].*", "\\1", "abc.com.foo.bar") # 1
## [1] "abc.com.foo"

library(tools)
file_path_sans_ext("abc.com.foo.bar") # 3
## [1] "abc.com.foo"

ADDED. Regarding your comment asking to remove leading periods, simplest is to just feed this into any of the above where x is the input string:

sub("^[.]*", "", x)

To do any of them in one line:

x <- c("abc.com.foo.bar", ".abc.com.foo.bar", ".vimrc")

sub("^[.]*(.*)[.]?.*$", "\\1", x) # 1a
## [1] "abc.com.foo.bar" "abc.com.foo.bar" "vimrc"          

file_path_sans_ext(sub("^[.]*", "", x))
## [1] "abc.com.foo" "abc.com.foo" "vimrc" 

Answer 4

I cannot help you with r and I almost forgot perl, but this works both in JS (proof) and PHP

/\.[A-Za-z]+$/     -->    replace this with empty string ""
  ^    ^    ^
  |    |    |
  |    |    end of line
  |    only chars (you can add 0-9 if numbers are also present)
  dot before last chars

the syntax of regex is rather common, so I'm sure you can adopt it (maybe just get rid of /)