Re: [R] tapply

From: Weiwei Shi <helprhelp_at_gmail.com>
Date: Wed 22 Jun 2005 - 01:02:50 EST

hi
i tried all the methods suggested above: ave and rowsum with "with" function works for my situation. I think the problem might not be due to tapply.
My data z comes from
z<-y[y[[1]] %in% x[[2]], c(1,9)]

while z is supposed to have no entries for those non-matched between x and y.

however, when I run tapply, and the result also includes those non-matched entries. I use is.na function to remove those entry from z first and then use tapply again, but the result is the same: those NA's and those non-matched results are still there. That's what I mean by "it doesn't work".

Is there something I missed here so that z "implicitly" has some "trace" back to y dataset?

thanks,

On 6/20/05, Gabor Grothendieck <ggrothendieck@gmail.com> wrote:
> On 6/20/05, Weiwei Shi <helprhelp@gmail.com> wrote:
> > hi,
> > i have another question on tapply:
> > i have a dataset z like this:
> > 5540 389100307391 2600
> > 5541 389100307391 2600
> > 5542 389100307391 2600
> > 5543 389100307391 2600
> > 5544 389100307391 2600
> > 5546 381300302513 NA
> > 5547 387000307470 NA
> > 5548 387000307470 NA
> > 5549 387000307470 NA
> > 5550 387000307470 NA
> > 5551 387000307470 NA
> > 5552 387000307470 NA
> >
> > I want to sum the column 3 by column 2.
> > I removed NA by calling:
> > tapply(z[[3]], z[[2]], sum, na.rm=T)
> > but it does not work.
> >
> > then, i used
> > z1<-z[!is.na(z[[3]],]
> > and repeat
> > still doesn't work.
> >
> > please help.
> >
>
> Depending on what you want you may be able to use rowsum:
>
> - display only groups that have at least one non-NA with the sum
> being the sum of the non-NAs:
>
> with(na.omit(z), rowsum(V3, V2))
>
> - display all groups with the sum being NA if any member is NA:
>
> rowsum(z$V3, z$V2)
>

-- 
Weiwei Shi, Ph.D

"Did you always know?"
"No, I did not. But I believed..."
---Matrix III

______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Received on Wed Jun 22 01:58:53 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:32:56 EST