On Apr 30, 2010, at 5:44 PM, Sebastian Kruk wrote:
> Hi, i have a vector filled with names:
>
> [1] Alvaro Adela ...
> [25] Beatriz Berta ...
> ...
> [100000] ...
>
> I would like to drop last character in every name.
>
> I use the next program:
>
> for (i in 1:100000) {
> largo <- nchar(names[i]-1)
> names[i] <- substring (names[i],1,largo]
> }
>
> Is another and faster way of do it?
>
> Thanks,
>
> Sebastián.
As is the case with R, more than one, but the fastest may be:
names <- c("Alvaro Adela", "Beatriz Berta")
> gsub("^(.*).{1}$", "\\1", names)
[1] "Alvaro Adel" "Beatriz Bert"
Just to show that it works with entries of varying lengths:
> gsub("^(.*).{1}$", "\\1", c("ABC", "ABCD", "ABCDE", "ABCDEF"))
[1] "AB" "ABC" "ABCD" "ABCDE"
See ?gsub and ?regex
You could use substr(), but the arguments for substring lengths are not
vectorized, so the following won't work:
> substr(c("ABC", "ABCD", "ABCDE", "ABCDEF"), 1, nchar(names) - 1)
[1] "ABC" "ABCD" "ABCDE" "ABCDEF"
You would have to do something like this:
> as.vector(sapply(c("ABC", "ABCD", "ABCDE", "ABCDEF"),
function(x) substr(x, 1, nchar(x) - 1)))
[1] "AB" "ABC" "ABCD" "ABCDE"
See ?substr and ?nchar
HTH,
Marc Schwartz
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
