sub, gsub

sub(pattern, replacement, x)
gsub(pattern, replacement, x)
Replace the first occurrence of a pattern with sub or replace all occurrences with gsub.
  • pattern – A pattern to search for, which is assumed to be a regular expression. Use an additional argument fixed=TRUE to look for a pattern without using regular expressions.
  • replacement – A character string to replace the occurrence (or occurrences for gsub) of pattern.
  • x – A character vector to search for pattern. Each element will be searched separately.

Example. The simple example below does not make use of regular expressions.
> x <- c("This is a sentence about axis",
+        "A second pattern is also listed here")
> sub("is", "XY", x)
[1] "ThXY is a sentence about axis"       
[2] "A second pattern XY also listed here"
> gsub("is", "XY", x)
[1] "ThXY XY a sentence about axXY"       
[2] "A second pattern XY also lXYted here"

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