plyr (version 1.6)

mlply: Call function with arguments in array or data frame, returning a list.

Description

Call a multi-argument function with values taken from columns of an data frame or array, and combine results into a list

Usage

mlply(.data, .fun = NULL, ..., .expand = TRUE, .progress
  = "none", .parallel = FALSE)

Arguments

.data

matrix or data frame to use as source of arguments

.fun

function to be called with varying arguments

...

other arguments passed on to .fun

.expand

should output be 1d (expand = FALSE), with an element for each row; or nd (expand = TRUE), with a dimension for each variable.

.progress

name of the progress bar to use, see create_progress_bar

.parallel

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

Value

• list of results

Details

The m*ply functions are the plyr version of mapply, specialised according to the type of output they produce. These functions are just a convenient wrapper around a*ply with margins = 1 and .fun wrapped in splat.

This function combines the result into a list. 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

mlply(cbind(1:4, 4:1), rep)
mlply(cbind(1:4, times = 4:1), rep)

mlply(cbind(1:4, 4:1), seq)
mlply(cbind(1:4, length = 4:1), seq)
mlply(cbind(1:4, by = 4:1), seq, to = 20)