R help - Apr 2011 - indexing list elements with lapply?

Dear colleagues,
I have a list that looks like what the code below produces.  I  need a function
to go through each list element and work on the second column of each list
element (the first column is irrelevant to me...if the proposed function works
on the first column as a consequence of a writing something simple, that's
fine).
I need to index the second column of each list element to the first item in each
column.  So for each list, I need to divide each number in the second column by
the first number in that column.

This code does what I want, but it only works on one item in the list
r[[1]][,2] / r[[1]][1,2].

I've tried working with this function but can't get it to work: 
f<-function(x) {
for (i in 1:5)
{

x[[i]][,2]/x[[i]][1,2]
}
}

lapply(r, f)

But I get this error message:
Error in x[[i]][, 2] : incorrect number of dimensions

Hope someone can help. I'm grateful for any suggestions. 
Yours, Simon Kiss

******dataset

ff<-runif(10, 0.85, 1)
ff<-cbind(ff, 1-ff)
gg<-runif(10, 0.85, 1)
gg<-cbind(gg, 1-ff)
hh<-runif(10, 0.86, 1)
hh<-cbind(hh, 1-hh)
ii<-runif(10, 0.92, 1)
ii<-cbind(ii, 1-ii)
jj<-runif(10,0.76, 1)
jj<-cbind(jj, 1-jj)
r<-list(ff, gg, hh,ii, jj)
*********************************
Simon J. Kiss, PhD
Assistant Professor, Wilfrid Laurier University
73 George Street
Brantford, Ontario, Canada
N3T 2C9
Cell: +1 519 761 7606

Dear Simon,

Try any of the following:

sapply(r, function(l) l[,2] / l[1, 2])
lapply(r, function(l) l[,2] / l[1, 2])

HTH,
Jorge


On Fri, Apr 22, 2011 at 5:52 PM, Simon Kiss <> wrote:
> Dear colleagues,
> I have a list that looks like what the code below produces.  I  need a
> function to go through each list element and work on the second column of
> each list element (the first column is irrelevant to me...if the proposed
> function works on the first column as a consequence of a writing something
> simple, that's fine).
> I need to index the second column of each list element to the first item in
> each column.  So for each list, I need to divide each number in the second
> column by the first number in that column.
>
> This code does what I want, but it only works on one item in the list
> r[[1]][,2] / r[[1]][1,2].
>
> I've tried working with this function but can't get it to work:
> f<-function(x) {
> for (i in 1:5)
> {
>
> x[[i]][,2]/x[[i]][1,2]
> }
> }
>
> lapply(r, f)
>
> But I get this error message:
> Error in x[[i]][, 2] : incorrect number of dimensions
>
> Hope someone can help. I'm grateful for any suggestions.
> Yours, Simon Kiss
>
> ******dataset
>
> ff<-runif(10, 0.85, 1)
> ff<-cbind(ff, 1-ff)
> gg<-runif(10, 0.85, 1)
> gg<-cbind(gg, 1-ff)
> hh<-runif(10, 0.86, 1)
> hh<-cbind(hh, 1-hh)
> ii<-runif(10, 0.92, 1)
> ii<-cbind(ii, 1-ii)
> jj<-runif(10,0.76, 1)
> jj<-cbind(jj, 1-jj)
> r<-list(ff, gg, hh,ii, jj)
> *********************************
> Simon J. Kiss, PhD
> Assistant Professor, Wilfrid Laurier University
> 73 George Street
> Brantford, Ontario, Canada
> N3T 2C9
> Cell: +1 519 761 7606
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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