[R] how to use apply with a function created by ourselfs...?
ANA KOZOMARA
magnolia at absolutok.net
Mon Apr 21 11:43:19 CEST 2003
hey thanks a lot...
finally I decided to write my own fonction which will do it...
I was completely lost with rbind, mode="list"...
I find slightely weird the R-kind-of-thinking...:)))
Anyway, i'm trying to acomplish my project in R and not c spirit,
so i'll try what u suggests,
..hey, thanks a lot again...
______________________________________________________________________
Original poruka
Od: Peter Dalgaard BSA <p.dalgaard at biostat.ku.dk>
Za: ANA KOZOMARA <magnolia at absolutok.net>
Tema: Re: [R] how to use apply with a function created by ourselfs...?
Primljena: 21 Apr 2003 11:27:48
"ANA KOZOMARA" <magnolia at absolutok.net> writes:
> ..hey thanks for the answer, both of you...
> but :-(, I don't seem to have an answer to my problem...
> I tried with what u suggested, but it doesn't work yet...
> so I will precise it...
> I have a data frame...
> and I would like to apply the function "prediction" which acts on two
> vectors
> prediction(linear,ind),
> to my data frame,I mean to all the rows of my data frame...
> something like a function "Map" in Mathematica...
> Shortly, I want to apply function "prediction" to a list of arguments,
not
> to a single argument...
> I hope now it is more clear...
> Thanks for the answers once more,
> best regards,
> ana
It depends on your prediction function. The best thing is to arrange
that it vectorizes over its arguments, as Spencer Graves suggested.
Then it's just
prediction(df[,1],df[,2])
or, if you want something that works for more than two rows,
do.call("prediction", df)
if your prediction() does not vectorize (i.e. a and b has to be
scalars), you can do two things:
pr.row <- function(row) do.call("prediction",row)
apply(df, 1, pr.row)
or create a vectorized prediction(), as in
pr.vec <- function(a,b)
sapply(seq(along=a),function(i)prediction(a[i],b[i]))
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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