promoting scalar arguments to vectors in a function

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
Suppose I have a function that takes three numeric arguments x, y,  and z, any
of which may be scalars or vectors.
Suppose further that the user takes one of the arguments, say y, as a vector
with the other two as scalars.
Is there an existing R function that will promote the other two arguments to
vectors of the same size?

This depends on what you mean by 'promote' ...

If you want to do something like 'recycling', as is often done for plot colours, but need things the same length for subsetting etc, one crude but fairly straightforward way I will confess to using in a function is something like

L <- max( length(x), length(y), length(z) )
x <- rep(x, length.out=L) 
y <- rep(y, length.out=L) 
z <- rep(z, length.out=L)

If you wanted to zero-fill to the same length, or fill with NA, that'd be something else ...

S Ellison




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