[Rd] suggestion for addition to substring
pburns at pburns.seanet.com
Sun Jun 27 11:55:30 CEST 2004
Below is suggested code for adding a "tail" argument to the
Getting the end of a string is a fairly common operation in
finance where the exchange of an asset is often encoded.
This is a new implementation, but I don't think there are any
tricky bits I haven't thought of.
function (text, first, last = 1e+06, tail=NULL)
storage.mode(text) <- "character"
stop("only one of first and tail allowed")
nc <- nchar(text)
first <- nc - tail + 1
n <- max(lt <- length(text), length(first), length(last))
if (lt && lt < n)
text <- rep(text, length.out = n)
substr(text, first, last)
As implemented here "tail" gives the distance from the original end of the
strings, not the number of characters in the answer (when "last" is given).
patrick at burns-stat.com
+44 (0)20 8525 0696
(home of S Poetry and "A Guide for the Unwilling S User")
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