R: How to replace . in a string?

Question

I have a string say \"a.b\" and I want to replace \".\" with \"_\".

gsub(\".\",\"_\",\"a.b\")

doesn\'t work as . matches all characters.

Answer 1

Try [[:punct:]] regex syntax, as "." in itself is a punctuation character present in the string.

gsub("[[:punct:]]","_","a.b")

Output : [1] "a_b"

Answer 2

. matches any character. Escape . using \ to match . literally.

\ itself is also should be escaped:

> gsub("\\.", "_", "a.b")
[1] "a_b"

Answer 3

You need to double escape \\, escaping . to match the literal dot and escaping \ also. Keep in mind using sub replaces the first occurrence of a pattern, gsub replaces all occurrences.

string <- "a.b"
sub('\\.', '_', string)
[1] "a_b"

string <- "a.b.c.d.e.f"
gsub('\\.', '_', string)
[1] "a_b_c_d_e_f"

You can also use sub or gsub with the fixed = TRUE parameter. This takes the string representing the pattern you are searching for as it is ignoring special characters.

string <- "a.b"
sub('.', '_', string, fixed = TRUE)
[1] "a_b"

Answer 4

try like this :

gsub("[.]","_","a.b")