grep(pattern, x, ignore.case=FALSE, extended=TRUE, value=FALSE)
sub(pattern, replacement, x,
ignore.case=FALSE, extended=TRUE)
gsub(pattern, replacement, x,
ignore.case=FALSE, extended=TRUE)
pattern
|
character string containing a regular expression
to be matched in the vector of character string vec.
|
x
| a vector of character strings where matches is sought. |
ignore.case
|
if FALSE, the pattern matching is
case sensitive and if TRUE, case is ignored during matching.
|
extended
|
if TRUE, extended regular expression matching
is used, and if FALSE basic regular expressions are used.
|
value
|
if FALSE, a vector containing the indices
of the matches determined by grep is returned,
and if TRUE, a vector containing the matching
elements themselves is returned.
|
replacement
|
a replacement for matched pattern in
sub and gsub.
|
grep searches for matches to pattern given as its first
argument within the the vector of character strings given as
its second argument.
sub and gsub perform replacement of matches
determined by regular expression matching.
The functions differ only in that sub replaces only
the first occurence of a pattern whereas gsub replaces
all occurences.
The regular expressions used are those specified by POSIX 1003.2,
either extended or basic, depending on the value of the
extended argument.
match, pmatch.