Basic question on applying a function to each row of a da taframe

Another another neat way is:
 

DF <- data.frame(x=1:4, y=rep(1,4))
foo <- function(z,x,y)z[x]+z[y]
apply(DF,1,foo,x="x",y="y")

1 2 3 4 
2 3 4 5 
 
or
 

DF <- data.frame(x=1:4, y=rep(1,4))
foo <- function(z)z<-x+y
foo(DF)

[1] 2 3 4 5


"Liaw, Andy" <andy_liaw at merck.com> wrote:
Another neat way is:

with(DF, foo(x, w))

HTH,
Andy

-----Original Message-----
From: peter leonard [mailto:pfleonard at hotmail.com]
Sent: Sunday, June 08, 2003 4:35 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Basic question on applying a function to each row of a
dataframe


Hi,

I have a function foo(x,y) and a dataframe, DF, comprised of 
two vectors, x 
& w, as follows :

x w
1 1 1
2 2 1
3 3 1
4 4 1

etc


I would like to apply the function foo to each 'pair' within DF e.g 
foo(1,1), foo(2,1), foo(3,1) etc

I have tried

apply(DF,foo)
apply(DF[,],foo)
apply(DF[DF$x,DF$w],foo)

However, none of the above worked. Can anyone help ?

Thanks in advance,
Peter

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Yes, but very slow for this example when the data.frame gets large....