[R] Change array size
Tony Plate
tplate at blackmesacapital.com
Fri Feb 14 18:32:04 CET 2003
If you just want to extend the vector, and fill new elements with NA, then
a simple way is:
> x <- 1:5
> length(x) <- 2 ^ ceiling(log(length(x))/log(2))
> x
[1] 1 2 3 4 5 NA NA NA
>
However, one needs to be careful with kind of arithmetic -- floating point
inaccuracies can cause unexpected results. E.g., one would expect the
following points to form a straight line, but they don't -- on my computer
there are 4 anomalies between 29 and 50:
> plot(ceiling(log(2**(1:50))/log(2)))
In the question asked, this is unlikely to cause problems as it is unlikely
that a vector will have 2^29 elements.
At Friday 09:51 AM 2/14/2003 +0000, Poizot Emmanuel wrote:
>Hi,
>I would like to know if there is a way to change a vector of arbitrary size
>to make it fits the nearest upper size multiple of a power of 2.
>
>--
>Cordialy
>----------------------------------------
>Emmanuel POIZOT
>Cnam/Intechmer
>Digue de Collignon
>50110 Tourlaville
>Tél : (33)(0)2 33 88 73 42
>Fax : (33)(0)2 33 88 73 39
>-----------------------------------------
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>http://www.stat.math.ethz.ch/mailman/listinfo/r-help
More information about the R-help
mailing list