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plyr (version 1.6)

ldply: 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