R devel - Oct 2015 - rank(, ties.method="last")

Hi,

I ran into a problem where I actually need rank(, ties.method="last").
It would
be great to have this feature in base and it's also simple to get (see
below).

Thanks & cheers,
Marius


rank2 <- function (x, na.last = TRUE, ties.method = c("average",
"first", "last", # new "last"
    "random", "max", "min"))
{
    nas <- is.na(x)
    nm <- names(x)
    ties.method <- match.arg(ties.method)
    if (is.factor(x))
        x <- as.integer(x)
    x <- x[!nas]
    y <- switch(ties.method, average = , min = , max = .Internal(rank(x,
        length(x), ties.method)), first = sort.list(sort.list(x)),
        last = sort.list(sort.list(x, decreasing=TRUE),
decreasing=TRUE), # change
        random = sort.list(order(x, stats::runif(sum(!nas)))))
    if (!is.na(na.last) && any(nas)) {
        yy <- NA
        NAkeep <- (na.last == "keep")
        if (NAkeep || na.last) {
            yy[!nas] <- y
            if (!NAkeep)
                yy[nas] <- (length(y) + 1L):length(yy)
        }
        else {
            len <- sum(nas)
            yy[!nas] <- y + len
            yy[nas] <- seq_len(len)
        }
        y <- yy
        names(y) <- nm
    }
    else names(y) <- nm[!nas]
    y
}

## MWE
x <- c(10, 11, 11, 12, 12, 13)
rank(x, ties.method="first")
rank2(x, ties.method="last")

> I ran into a problem where I actually need rank(,
ties.method="last"). It would
> be great to have this feature in base and it's also simple to get (see
below).
> Thanks & cheers,
> Marius
> rank2 <- function (x, na.last = TRUE, ties.method =
c("average",
> "first", "last", # new "last"
>     "random", "max", "min"))
> {
>     nas <- is.na(x)
>     nm <- names(x)
>     ties.method <- match.arg(ties.method)
>     if (is.factor(x))
>         x <- as.integer(x)
>     x <- x[!nas]
>     y <- switch(ties.method, average = , min = , max = .Internal(rank(x,
>         length(x), ties.method)), first = sort.list(sort.list(x)),
>         last = sort.list(sort.list(x, decreasing=TRUE), decreasing=TRUE), #
change
>         random = sort.list(order(x, stats::runif(sum(!nas)))))
>     if (!is.na(na.last) && any(nas)) {
>         yy <- NA
>         NAkeep <- (na.last == "keep")
>         if (NAkeep || na.last) {
>             yy[!nas] <- y
>             if (!NAkeep)
>                 yy[nas] <- (length(y) + 1L):length(yy)
>         }
>         else {
>             len <- sum(nas)
>             yy[!nas] <- y + len
>             yy[nas] <- seq_len(len)
>         }
>         y <- yy
>         names(y) <- nm
>     }
>     else names(y) <- nm[!nas]
>     y
> }
> ## MWE
> x <- c(10, 11, 11, 12, 12, 13)
> rank(x, ties.method="first")
> rank2(x, ties.method="last")
Indeed, this makes sense to me, and is easy enough to document
and maintain, and preferable to asking useRs to use  rev(.) and
similar "easy" (but somewhat costly for large data!)
transformations to get the same....

Or have (Marius Hofert and I) overlooked something obvious ?

Martin Maechler,
ETH Zurich

Den 2015-10-09 kl. 12:14, skrev Martin Maechler:
>
>> I ran into a problem where I actually need rank(,
ties.method="last"). It would
>> be great to have this feature in base and it's also simple to get
(see below).
>
>> Thanks & cheers,
>> Marius
>
>
>> rank2 <- function (x, na.last = TRUE, ties.method =
c("average",
>> "first", "last", # new "last"
>>      "random", "max", "min"))
>> {
>>      nas <- is.na(x)
>>      nm <- names(x)
>>      ties.method <- match.arg(ties.method)
>>      if (is.factor(x))
>>          x <- as.integer(x)
>>      x <- x[!nas]
>>      y <- switch(ties.method, average = , min = , max =
.Internal(rank(x,
>>          length(x), ties.method)), first = sort.list(sort.list(x)),
>>          last = sort.list(sort.list(x, decreasing=TRUE),
decreasing=TRUE), # change
>>          random = sort.list(order(x, stats::runif(sum(!nas)))))
>>      if (!is.na(na.last) && any(nas)) {
>>          yy <- NA
>>          NAkeep <- (na.last == "keep")
>>          if (NAkeep || na.last) {
>>              yy[!nas] <- y
>>              if (!NAkeep)
>>                  yy[nas] <- (length(y) + 1L):length(yy)
>>          }
>>          else {
>>              len <- sum(nas)
>>              yy[!nas] <- y + len
>>              yy[nas] <- seq_len(len)
>>          }
>>          y <- yy
>>          names(y) <- nm
>>      }
>>      else names(y) <- nm[!nas]
>>      y
>> }
>
>> ## MWE
>> x <- c(10, 11, 11, 12, 12, 13)
>> rank(x, ties.method="first")
>> rank2(x, ties.method="last")
>
> Indeed, this makes sense to me, and is easy enough to document
> and maintain, and preferable to asking useRs to use  rev(.) and
> similar "easy" (but somewhat costly for large data!)
> transformations to get the same....
>
> Or have (Marius Hofert and I) overlooked something obvious ?
I think so: the code above doesn't seem to do the right thing.  Consider 
the following example:

 > x <- c(1, 1, 2, 3)
 > rank2(x, ties.method = "last")
[1] 1 2 4 3

That doesn't look right to me -- I had expected

 > rev(sort.list(x, decreasing = TRUE))
[1] 2 1 3 4


Henric Winell


>
> Martin Maechler,
> ETH Zurich
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

On Tue, Oct 20, 2015 at 10:26 AM, Henric Winell
<nilsson.henric at gmail.com> wrote:
> Den 2015-10-09 kl. 12:14, skrev Martin Maechler:
> I think so: the code above doesn't seem to do the right thing. 
Consider
> the following example:
>
>  > x <- c(1, 1, 2, 3)
>  > rank2(x, ties.method = "last")
> [1] 1 2 4 3
>
> That doesn't look right to me -- I had expected
>
>  > rev(sort.list(x, decreasing = TRUE))
> [1] 2 1 3 4
>
Indeed, well spotted, that seems to be correct.
>
> Henric Winell
>