[R] Extending a vector to length n

[Raubertas, Richard]

The following approach works for both of your examples:

xx <- rep(x, length.out=n)
xx[m:n] <- NA

Thus:

> n <- 2
> aa <- rep(a, length.out=n)
> aa[(length(a)+1):n] <- NA
> aa
[1] "2008-01-01" NA          
> bb <- rep(b, length.out=n)
> bb[(length(b)+1):n] <- NA
> bb
[1] a    <NA>
Levels: a
>

R. Raubertas
Merck & Co
 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of hadley wickham
> Sent: Wednesday, April 15, 2009 10:55 AM
> To: r-help
> Subject: [R] Extending a vector to length n
> 
> In general, how can I increase a vector of length m (< n) to length n
> by padding it with m - n missing values, without losing attributes?
> The two approaches I've tried, using length<- and adding missings with
> c, do not work in general:
> 
> > a <- as.Date("2008-01-01")
> > c(a, NA)
> [1] "2008-01-01" NA
> > length(a) <- 2
> > a
> [1] 13879    NA
> 
> 
> > b <- factor("a")
> > c(b, NA)
> [1]  1 NA
> > length(b) <- 2
> > b
> [1] a    <NA>
> Levels: a
> 
> Hadley
> 
> 
> 
> -- 
> http://had.co.nz/
> 
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