This sounds like a perfect use of "list" and the 'sapply/lapply' functions:
> # list with 100 dataframes
> df.list <- lapply(1:100,function(x) data.frame(a=1:10, b=1:10))
> # create a new list with a random value of 'a'
> new.list <- sapply(df.list, function(x) sample(x$a, 1))
>
>
> new.list
[1] 5 8 10 4 8 10 3 7 2 3 4 1 4 9 4 5 6 5 2 9 7 8 2
8 5 9 7 8 6 6 8 1 5 8 7
[36] 5 9 5 3 1 1 4 6 7 5 10 3 5 4 7 3 5 8 1 9 4 9 4
4 5 9 9 4 8 10 5 8 4 4 8
[71] 3 8 2 3 2 3 1 7 9 8 8 5 5 9 7 7 4 3 10 7 3 2 5
10 6 10 8 4 5 2
>
On Tue, May 18, 2010 at 5:28 PM, Q <quaga...@gmail.com> wrote:
>
> Hello!
>
>
> I'm having trouble figuring out how to apply a function to a set of vectors
> or data frames, when that set is over 1000 large.
>
>
> I've created 1891 vectors named as follows:
>
>
> vector.names <- paste("vector",1:1891,sep="")
>
>
> These can be referred to easily by using get as follows:
>
>
> vector <- get(vector.names[1])
>
>
> The problem is, I can't figure out a way to refer to all of them as a
> group,
> and then apply a function to each one. Basically, I have 5000 data frames,
> each with 1891 rows. I want a vector for each row, and a cell from each
> data frame in each vector. That would give me 1891 vectors with 5000
> members each. The only way I know how to do this, is to use loops, which
> end up being really slow.
>
>
> So:
>
>
> for(a in 1:5000){
>
> data <- get(dataframes[a])
>
>
> for(b in 1:1891){
>
> vector <- get(vector.names[b]
>
> vector[a] <- data$value
>
> assign(vector.names[b], vector)
>
> }
>
>
> }
>
>
> Does anyone have any insight into dealing with large quantities of data
> like
> this?
>
>
> Thanks!
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Dealing-with-1000-sequentially-named-vectors-tp2221942p2221942.html
> Sent from the R help mailing list archive at Nabble.com.
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> 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<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
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