Colleagues
I appreciate the many suggestions for my query about collapsing a sequence to a
shortened string.
I finally arrived at:
format_ranges <- function(x)
{
x <- sort(unique(x))
breaks <- which(diff(x) > 1)
start_idx <- c(1, breaks + 1)
end_idx <- c(breaks, length(x))
ranges <- mapply(function(s, e)
{
if (s == e) return(as.character(x[s]))
else return(paste(x[s], x[e], sep="-"))
}, start_idx, end_idx)
paste(ranges, collapse=", ")
}
numbers <- c(1, 3, 4, 5, 7, 8, 12, 13, 14, 15, 20)
cat("original sequence is:\t\t", numbers, "\n")
cat("collapsed text string is:\t", format_ranges(numbers), "\n")
Dennis
Dennis Fisher MD
P < (The "P Less Than" Company)
Phone / Fax: 1-866-PLessThan (1-866-753-7784)
www.PLessThan.com
> On Feb 22, 2025, at 8:14 AM, Bert Gunter <bgunter.4...@gmail.com> wrote:
>
> Well, as I predicted, my initial suggestions were, ... ummm, rather dumb.
> Also, Rui's suggestions are probably preferable to the below. However, it
> *is* a very simple, bare-boned approach to converting a sequence of
> increasing integers to a character representation using interval notation.
> The code is *very* simple-minded and needs no explanation, I think. You
> should also be able to easily tweak it to change the output format from my
> paste0(..., collapse) choice to something else.
>
> compr <- function(x, sep ="-", collapse = ", ")
> {
> left<- c(TRUE, diff(x) != 1)
> right <- c(rev(diff(rev(x)) != -1 ), TRUE)
> xleft <- x[left]
> xright <- x[right]
> ifelse(xleft == xright,
> xleft,
> paste(xleft, xright, sep = sep)) |>
> paste0(collapse = collapse)
> }
>
> which yields the following with your example
>
> > compr(c( 1, 3, 4, 5, 7, 8, 12, 13, 14, 15, 20))
> [1] "1, 3-5, 7-8, 12-15, 20" ##Note: A single character string
>
> (Do let me know if this can fail)
> Cheers,
> Bert
>
> "An educated person is one who can entertain new ideas, entertain others, and
> entertain herself."
>
>
>
> On Sat, Feb 22, 2025 at 4:36 AM Rui Barradas <ruipbarra...@sapo.pt> wrote:
> Às 00:46 de 22/02/2025, Dennis Fisher escreveu:
> > R 4.4.0
> > OS X
> >
> > Colleagues
> >
> > I have a sequence like:
> > 1, 3, 4, 5, 7, 8, 12, 13, 14, 15, 20
> >
> > I would like to display it as:
> > 1, 3-5, 7-8, 12-15, 20
> >
> > Any simple ways to accomplish this?
> >
> > Dennis
> >
> >
> > Dennis Fisher MD
> > P < (The "P Less Than" Company)
> > Phone / Fax: 1-866-PLessThan (1-866-753-7784)
> > www.PLessThan.com
> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> > https://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> Hello,
>
> Here is a way with package R.utils, function seqToIntervals.
>
>
> x <- scan(text = "1, 3, 4, 5, 7, 8, 12, 13, 14, 15, 20", sep = ",")
>
> mat <- R.utils::seqToIntervals(x)
> apply(mat, 1L, \(m) {
> ifelse(m[1L] == m[2L], m[1L], paste(m, collapse = "-"))
> })
> #> [1] "1" "3-5" "7-8" "12-15" "20"
>
>
> If you want to be fancy, define a special class that prints like that.
>
>
>
> x <- scan(text = "1, 3, 4, 5, 7, 8, 12, 13, 14, 15, 20", sep = ",")
>
> as_seqInterval <- function(x) {
> old_class <- class(x)
> class(x) <- c("seqInterval", old_class)
> x
> }
> print.seqInterval <- function(x, ...) {
> mat <- R.utils::seqToIntervals(x)
> out <- apply(mat, 1L, \(m) {
> ifelse(m[1L] == m[2L], m[1L], paste(m, collapse = "-"))
> })
> print(out)
> }
>
> y <- as_seqInterval(x)
> class(y)
> #> [1] "seqInterval" "numeric"
>
> # autoprinting y
> y
> #> [1] "1" "3-5" "7-8" "12-15" "20"
>
> # explicit printing y
> print(y)
> #> [1] "1" "3-5" "7-8" "12-15" "20"
>
>
> Hope this helps,
>
> Rui Barradas
>
>
> --
> Este e-mail foi analisado pelo software antivírus AVG para verificar a
> presença de vírus.
> www.avg.com
>
> ______________________________________________
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
