alply {plyr}R Documentation

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

Description

For each slice of an array, apply function then combine results into a list

Usage

alply(.data, .margins, .fun = NULL, ..., .progress = "none")

Arguments

.data matrix, array or data frame to be processed
.margins a vector giving the subscripts to split up data by. 1 splits up by rows, 2 by columns and c(1,2) by rows and columns, and so on for higher dimensions
.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

Details

All plyr functions use the same split-apply-combine strategy: they split the input into simpler pieces, apply .fun to each piece, and then combine the pieces into a single data structure. This function splits matrices, arrays and data frames by dimensions and combines the result into a list. If there are no results, then this function will return a list of length 0 (list()).

alply is somewhat similar to apply for cases where the results are not atomic.

@keyword manip @arguments matrix, array or data frame to be processed @arguments a vector giving the subscripts to split up data by. 1 splits up by rows, 2 by columns and c(1,2) by rows and columns, and so on for higher dimensions @arguments function to apply to each piece @arguments other arguments passed on to .fun @arguments name of the progress bar to use, see create_progress_bar @value list of results

Value

list of results

Author(s)

Hadley Wickham <h.wickham@gmail.com>

Examples

alply(ozone, 3, quantile)
alply(ozone, 3, function(x) table(round(x)))

[Package plyr version 0.1.5 Index]