[R] A problem with using the "outer" function

Thomas Lumley tlumley at u.washington.edu
Thu Jul 10 17:33:52 CEST 2003

On Wed, 9 Jul 2003, Duncan Murdoch wrote:

> On Wed, 09 Jul 2003 15:33:11 -0400, Ravi Varadhan <rvaradha at jhsph.edu>
> wrote :
> >Hi:
> >
> >I am using R 1.7.0 on Windows.  I am having trouble getting "outer" to
> >work on one of my functions.
> Most likely the problem is that the function you give doesn't work on
> array arguments.  Your function needs to take two arrays of the same
> shape as the first two arguments, and return an array of answers.
> outer() doesn't work by looping, it works by constructing big arrays
> of inputs and making just one function call.

Two further notes:

1/ This is in the FAQ.

2/ It is possible to use mapply() to vectorise an arbitrary function.
There isn't any speed advantage in doing so, but it will then work with


Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle

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