R: Split list, apply function, and return results in a list.

llply {plyr}

R Documentation

Split list, apply function, and return results in a list.

Description

For each element of a list, apply function, keeping results as a list.

Usage

llply(.data, .fun = NULL, ..., .progress = "none", .inform = FALSE,
  .parallel = FALSE, .paropts = NULL)

Arguments

`.data`	list to be processed
`.fun`	function to apply to each piece
`...`	other arguments passed on to `.fun`
`.progress`	name of the progress bar to use, see `create_progress_bar`
`.inform`	produce informative error messages? This is turned off by default because it substantially slows processing speed, but is very useful for debugging
`.parallel`	if `TRUE`, apply function in parallel, using parallel backend provided by foreach
`.paropts`	a list of additional options passed into the `foreach` function when parallel computation is enabled. This is important if (for example) your code relies on external data or packages: use the `.export` and `.packages` arguments to supply them so that all cluster nodes have the correct environment set up for computing.

Details

llply is equivalent to lapply except that it will preserve labels and can display a progress bar.

Value

list of results

Input

This function splits lists by elements.

Output

If there are no results, then this function will return a list of length 0 (list()).

References

Hadley Wickham (2011). The Split-Apply-Combine Strategy for Data Analysis. Journal of Statistical Software, 40(1), 1-29. http://www.jstatsoft.org/v40/i01/.

Examples

llply(llply(mtcars, round), table)
llply(baseball, summary)
# Examples from ?lapply
x <- list(a = 1:10, beta = exp(-3:3), logic = c(TRUE,FALSE,FALSE,TRUE))

llply(x, mean)
llply(x, quantile, probs = 1:3/4)

[Package plyr version 1.8.4 Index]