[R] filtering values

Thomas Lumley thomas at biostat.washington.edu
Wed Jul 5 17:49:04 CEST 2000

On Wed, 5 Jul 2000, amorgan wrote:

> I was wondering if there is a simple way to filter out a bunch of
> specific vales from a vector (eg zero).

x[x!=42] removes all the 42s 
x[!is.na(x)] removes all the NAs

> Also, is there a way to create a null vector?  What I mean by this is
> that if I declare a vector vector <- NA, it is a vector with [NA].  I
> want an empty vector, so that I can append to it later.

numeric(0) is a vector of length 0. Remember that repeatedly appending is
slower than creating a vector and then putting things in it.


Thomas Lumley
Assistant Professor, Biostatistics
University of Washington, Seattle

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