[Rd] On base::rank

[Martin Maechler]

>>>>> Arunkumar Srinivasan <arunkumar.sriniv at gmail.com>
>>>>>     on Thu, 8 Jan 2015 13:46:57 +0100 writes:

> Have a look at the following, taken from base::rank:

> ...
>     if (!is.na(na.last) && any(nas)) {
>         yy <- integer(length(x)) # <~~~~~~~~~
>         storage.mode(yy) <- storage.mode(y) # <~~~~~~~~
>         yy <- NA
>         NAkeep <- (na.last == "keep")
>         if (NAkeep || na.last) {
>             yy[!nas] <- y
>             if (!NAkeep)
>                 yy[nas] <- (length(y) + 1L):length(yy)
>         }
> ...

> Alternatively, look at lines 36 and 37 here:
> https://github.com/wch/r-source/blob/fbf5cdf29d923395b537a9893f46af1aa75e38f3/src/library/base/R/rank.R#L36

> There seems to be no need for those lines, IIUC. Isn't it? 
> 'yy' is replaced with NA in the ver next line.

Indeed.   Interesting that nobody has noticed till now,
even though that part has been world readable since at least 2008-08-25.

Note that the R source code is at 
     http://svn.r-project.org/R/
and the file in question at
     http://svn.r-project.org/R/trunk/src/library/base/R/rank.R

where you can already see the new code
(given that 'x' was no longer needed, there's no need for 'xx').

Martin Maechler, 
ETH Zurich