R devel - Mar 2011 - two minor bugs in rowsum()

(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?

(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

(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.)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

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

Hi,

On 03/29/2011 01:24 AM, Prof Brian Ripley wrote:
> On Fri, 25 Mar 2011, William Dunlap wrote:
[...]
>
>> (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 ...
Another problem with the current naming is the inconsistent use of
the row/col prefixes, IMO:

 > x <- matrix(runif(100), ncol=5)
 > rowsum(x, rep(1, 20))
       [,1]     [,2]    [,3]     [,4]     [,5]
1 11.13374 10.50038 10.0258 11.04087 8.150401
 > colSums(x)
[1] 11.133738 10.500381 10.025805 11.040867  8.150401

and the fact that the See Also section points to rowSums and not
colSums, which adds to the confusion...

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

-- 
Herv? Pag?s

Program in Computational Biology
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