[R] sum() with na.rm=TRUE, again
Liaw, Andy
andy_liaw at merck.com
Thu Apr 25 18:10:17 CEST 2002
After stripping NAs, you have a vector of 0 elements. Sum of such vector is
0, not NA. Try:
sum(numeric(0))
Andy
> -----Original Message-----
> From: Richards, Tom [mailto:richards at upci.pitt.edu]
> Sent: Thursday, April 25, 2002 11:26 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] sum() with na.rm=TRUE, again
>
>
> Hi:
>
> I remember a post several days ago by Jon Baron, concerning the
> behavior of sum() when one sets na.rm=TRUE:
> the result will be a zero sum for a vector of all NA's, as
> here, for the
> second row:
>
> > ss<- data.frame(x=c(1,NA,3,4),y=c(2,NA,4,NA))
> > ss
> x y
> 1 1 2
> 2 NA NA
> 3 3 4
> 4 4 NA
>
> > apply(ss,1,sum,na.rm=TRUE)
> 1 2 3 4
> 3 0 7 4
>
> I am rather alarmed by that zero, because I was just about to
> place the sum
> function into am apply() on a rather large data management
> project, where
> about 5% of my matrix rows have two missing values. Is there
> a "safe" way
> to use sum(), so that such zeroes are not created? A
> safe.sum() that takes
> arguments just as general as sum()? I mean, I think I could
> get around this
> little problem like this,
>
> apply(ss,1,function(x){ifelse(all(is.na(x)),NA,sum(!is.na(x))*
> mean(x,na.rm=T
> RUE))})
> 1 2 3 4
> 3 NA 7 4
>
> but is there a safer way to write a sum() function? Or, do
> these zeroes
> serve some purpose that I am missing?
> Thanks in advance...
>
> Tom
> -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.
> -.-.-.-.-.-.-.-.-
> r-help mailing list -- Read
> http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
> Send "info", "help", or "[un]subscribe"
> (in the "body", not the subject !) To:
> r-help-request at stat.math.ethz.ch
> _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._.
> _._._._._._._._._
>
------------------------------------------------------------------------------
Notice: This e-mail message, together with any attachments, contains information of Merck & Co., Inc. (Whitehouse Station, New Jersey, USA) that may be confidential, proprietary copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named on this message. If you are not the intended recipient, and have received this message in error, please immediately return this by e-mail and then delete it.
==============================================================================
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
More information about the R-help
mailing list