substr                 package:base                 R Documentation

Substrings of a Character Vector

Description:

     Extract or replace substrings in a character vector.

Usage:

     substr(x, start, stop)
     substring(text, first, last = 1000000)
     substr(x, start, stop) <- value
     substring(text, first, last = 1000000) <- value

Arguments:

 x, text: a character vector

start, first: integer. The first element to be replaced.

stop, last: integer. The last element to be replaced.

   value: a character vector, recycled if necessary.

Details:

     `substring' is compatible with S, with `first' and `last' instead
     of `start' and `stop'. For vector arguments, it expands the
     arguments cyclically to the length of the longest.

     When extracting, if `start' is larger than the string length then
     `""' is returned.

     For the replacement functions, if `start' is larger than the
     string length then no replacement is done.  If the portion to be
     replaced is longer than the replacement string, then only the
     portion the length of the string is replaced.

Value:

     For `substr', a character vector of the same length as `x'.

     For `substring', a character vector of length the longest of the
     arguments.

Note:

     The S4 version of `substring<-' ignores `last'; this version does
     not.

See Also:

     `strsplit', `paste', `nchar'.

Examples:

     substr("abcdef",2,4)
     print(ss <- substring("abcdef",1:6,1:6))
     stopifnot(ss == strsplit ("abcdef",NULL)[[1]])
     ## strsplit is more efficient ...

     substr(rep("abcdef",4),1:4,4:5)
     x <- c("asfef", "qwerty", "yuiop[", "b", "stuff.blah.yech")
     stopifnot(substr(x, 2, 5) == substring(x, 2, 5))
     substr(x, 2, 5)
     substring(x, 2, 4:6)

     substring(x, 2) <- c("..", "+++")
     x

