Re: [Rd] two minor bugs in rowsum()

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Tue, 29 Mar 2011 09:24:47 +0100 (BST)

On Fri, 25 Mar 2011, William Dunlap wrote:

> (a) In R 2.12.2 rowsum can overflow if given an integer input:
> > rowsum(c(2e9L, 2e9L), c("a", "a"))
> [,1]
> a -294967296
> > 2^32 + .Last.value
> [,1]
> a 4e+09
> Should it be changed to coerce its x argument to numeric
> (double precision) so it always returns a numeric output?

No, I don't think so. But it should return NA on overflow (as sum() does), and I've altered pre-2.13.0 to do so.

> (b) When rowsum is given an x containing both NaN and NA it
> appears to use the last of the NaN/NA entries to determine
> if the output is NaN or NA while the `+` function uses the
> first:
> > z <- cbind( c(NA,NA), c(NA,NaN), c(NaN,NA), c(NaN,NaN))
> > rowsum(z, c("a","a"))
> [,1] [,2] [,3] [,4]
> a NA NaN NA NaN
> > z[1,,drop=FALSE] + z[2,,drop=FALSE]
> [,1] [,2] [,3] [,4]
> [1,] NA NA NaN NaN

Which is not a bug: R does not claim to be consistent about this (except for a few documented functions), and there are lots of instances of this.

> (The name rowsum is a metabug, since it may be confused
> with the entirely different rowSums, but it has been around
> for a long time.)

A lot longer than rowSums ...

> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com

-- 
Brian D. Ripley,                  ripley_at_stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

______________________________________________
R-devel_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
Received on Tue 29 Mar 2011 - 08:28:13 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Tue 29 Mar 2011 - 19:30:39 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-devel. Please read the posting guide before posting to the list.

list of date sections of archive