[R] filling values in a vector using smaller vector
pburns at pburns.seanet.com
Wed Dec 24 10:35:27 CET 2008
I believe the following does what is wanted:
desired <- large
desired[large] <- small
patrick at burns-stat.com
+44 (0)20 8525 0696
(home of S Poetry and "A Guide for the Unwilling S User")
Milton Huang wrote:
> Dear list members:
> I am looking for an elegant (or efficient) way to accomplish the following:
> take a large boolean vector and fill the TRUE values with the values from a
> smaller boolean vector that has a length that is the number of TRUE values of
> the large vector.
> large<- c(FALSE, FALSE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, FALSE,
> TRUE, FALSE)
> small<- c(TRUE, FALSE, TRUE)
> desired output = c(FALSE, FALSE, FALSE, *TRUE*, FALSE, FALSE, *FALSE*, FALSE,
> FALSE, FALSE, *TRUE*, FALSE)
> (without the asterisks! )
> my first thought as someone new to R was
> ifelse(large,small, large)
> but that returns: c(FALSE FALSE FALSE TRUE FALSE FALSE TRUE FALSE FALSE
> FALSE FALSE FALSE) because small is cycled to match the size of large instead
> of the size of the TRUE subset of large.
> I am guessing that there is probably a way to do this without writing a loop,
> but I just don't know the syntax.
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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