?do.call
On Thu, May 24, 2012 at 9:32 AM, Alexander Shenkin <ashen...@ufl.edu> wrote:
> Hello Folks,
>
> Is there any way to pass a list into a function such that the function
> will use the list as its arguments? I haven't been able to figure that out.
>
> The background: I'm trying to build a function that will apply another
> function multiple times, each time with a different set of specified
> arguments. I'm trying to figure out how to pass in a list of argument
> lists, then loop through the top-level list, passing in the lower-level
> list as function arguments.
>
> pseudocode:
>
> b = list( list( arg1 = 1, arg2 = 2 ),
> list( arg1 = 3, arg2 = 4 )
> )
>
> a <- apply_function(arglist) {
> for (i in length(arglist)) {
> b(arglist[i])
> }
> }
>
>
> Specifically, the actual use I'm trying to implement is a function to
> format columns of data frames and matrices independently. What I have
> so far is below, but it's not working. Perhaps I'm going about this the
> wrong way?
>
>
> format_cols <- function(x, format_list = list()) {
> # usage: length(format_list) must equal ncol(x)
> # format list should be a list of lists of key=value pairs
> corresponding to format settings for each column
>
> if (is.data.frame(x)) {
> newout = data.frame()
> } else if (is.matrix(x)) {
> newout = matrix()
> }
>
> for (i in 1:ncol(x)){
> newout = cbind(newout, format(x,format_list[[i]]))
> x[,i] = format(x,format_list[[i]])
> }
> return(newout)
> }
>
> Thanks,
> Allie
>
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--
Gregory (Greg) L. Snow Ph.D.
538...@gmail.com
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