R help - Mar 2006 - tapply with unequal length of arguments

Hi everyone,

Is it possible to use tapply(x,y,mean) if not all groups of x by y are 
of the same length (for example if you have one missing observation)?

I tried tapply(x,y,mean,na.omit=T) but it doesn't work!

Steffi
-- 
---------------------------------
Stefanie von Felten
Doktorandin

ETH Z?rich
Institut f?r Pflanzenwissenschaften
ETH Zentrum, LFW A 2

Telefon: 044 632 85 97
Telefax: 044 632 11 53
e-mail:  stefanie.vonfelten at ipw.agrl.ethz.ch
http://www.ipw.agrl.ethz.ch/~svfelten/

und:

Universit?t Z?rich
Institut f?r Umweltwissenschaften
Winterthurerstrasse 190
8057 Z?rich

Telefon: 044 635 61 23
Telefax: 044 635 57 11
e-mail:  sfelten at uwinst.unizh.ch
http://www.unizh.ch/uwinst/homepages/steffi.html

2006/3/12, Stefanie von Felten, IPW&IfU <sfelten at
uwinst.unizh.ch>:
> Hi everyone,
>
> Is it possible to use tapply(x,y,mean) if not all groups of x by y are
> of the same length (for example if you have one missing observation)?
Yes,It works.
> I tried tapply(x,y,mean,na.omit=T) but it doesn't work!
What does "it doesn't work" mean exactly?Can you give an example
and
the error msg?
> Steffi
> --
> ---------------------------------
> Stefanie von Felten
> Doktorandin
>
> ETH Z?rich
> Institut f?r Pflanzenwissenschaften
> ETH Zentrum, LFW A 2
>
> Telefon: 044 632 85 97
> Telefax: 044 632 11 53
> e-mail:  stefanie.vonfelten at ipw.agrl.ethz.ch
> http://www.ipw.agrl.ethz.ch/~svfelten/
>
> und:
>
> Universit?t Z?rich
> Institut f?r Umweltwissenschaften
> Winterthurerstrasse 190
> 8057 Z?rich
>
> Telefon: 044 635 61 23
> Telefax: 044 635 57 11
> e-mail:  sfelten at uwinst.unizh.ch
> http://www.unizh.ch/uwinst/homepages/steffi.html
>
> ______________________________________________
> R-help at 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
>

--
???
Deparment of Sociology
Fudan University

Stefanie von Felten, IPW&IfU wrote:
> Hi everyone,
> 
> Is it possible to use tapply(x,y,mean) if not all groups of x by y are 
> of the same length (for example if you have one missing observation)?
> 
> I tried tapply(x,y,mean,na.omit=T) but it doesn't work!

See ?tapply which tells you that the argument "..." is passed to FUN 
which is mean() in this case. mean() has an argument "na.rm", see
?mean.
So we get:

  tapply(x, y, mean, na.rm = TRUE)

Please read the help pages more carefully.

Uwe Ligges
> Steffi