ldply {plyr}R Documentation

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

Description

For each element of a list, apply function then combine results into a data frame.

Usage

  ldply(.data, .fun = NULL, ..., .progress = "none",
    .parallel = FALSE)

Arguments

.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

.data

list to be processed

.parallel

if TRUE, apply function in parallel, using parallel backend provided by foreach

Value

A data frame, as described in the output section.

Input

This function splits lists by elements and combines the result into a data frame.

Output

The most unambiguous behaviour is achieved when .fun returns a data frame - in that case pieces will be combined with rbind.fill. If .fun returns an atomic vector of fixed length, it will be rbinded together and converted to a data frame. Any other values will result in an error.

If there are no results, then this function will return a data frame with zero rows and columns (data.frame()).

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/.

See Also

Other data frame output: adply, ddply

Other list input: laply, llply


[Package plyr version 1.7.1 Index]