[R-pkgs] plyr: version 1.2

From: Hadley Wickham <hadley_at_rice.edu>
Date: Fri, 10 Sep 2010 07:36:20 -0500

plyr is a set of tools for a common set of problems: you need to __split__ up a big data structure into homogeneous pieces, __apply__ a function to each piece and then __combine__ all the results back together. For example, you might want to:

It's already possible to do this with base R functions (like split and the apply family of functions), but plyr makes it all a bit easier with:

Considerable effort has been put into making plyr fast and memory efficient, and in many cases plyr is as fast as, or faster than, the built-in functions.

You can find out more at http://had.co.nz/plyr/, including a 20 page introductory guide, http://had.co.nz/plyr/plyr-intro.pdf. You can ask questions about plyr (and data-manipulation in general) on the plyr mailing list. Sign up at http://groups.google.com/group/manipulatr

Version 1.2 (2010-09-09)


  x <- seq_len(20)
  wait <- function(i) Sys.sleep(0.1)
  system.time(llply(x, wait))
  # user system elapsed
  # 0.007 0.005 2.005

  system.time(llply(x, wait, .parallel = TRUE))   # user system elapsed
  # 0.020 0.011 1.038

  This work has been generously supported by BD (Becton Dickinson).



Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University

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Received on Fri 10 Sep 2010 - 22:41:10 EST

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