Hello,
I think I have a mental block when it comes to working with lists. lapply and
sapply appear to do some magical things, but I can't seem to master their usage.
As an example, I would like to convert a column within a list to a matrix, with
the list element corresponding to the new matrix column.
#Here is a simplified example: .
test=vector("list", 3)
for (i in 1:3){ test[[i]]=cbind(runif(15), rnorm(15,2)) } #create example list
(I'm sure there is a better way to do this too).
#Now, I wan to get the second column back out, converting it from a list to a
matrix. This works, but gets confusing/inefficient when I have multiple
complex lists I am trying to manage.
savecol2=matrix(0,15,0)
for (i in 1:3){
savecol2=cbind(savecol2, test[[i]][,1])
}
#Something like??: (of course this doesn't work)
savecol2=sapply(test, "[[", function(x) x[2,])
Thank you!
Jeff
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