[R] convert to binary to decimal
Marc Schwartz
marc_schwartz at comcast.net
Thu Feb 15 17:10:21 CET 2007
On Thu, 2007-02-15 at 16:38 +0100, Martin Feldkircher wrote:
> Hello,
> we need to convert a logical vector to a (decimal) integer. Example:
>
> a=c(TRUE, FALSE, TRUE) (binary number 101)
>
> the function we are looking for should return
>
> dec2bin(a)=5
>
> Is there a package for such a function or is it even implemented in the
> base package? We found the hexmode and octmode command, but not a
> binmode. We know how to program it ourselves however we are looking for
> a computationally efficient algorithm.
>
> Martin and Stefan
This is a modification of a function that I had posted a while back, so
that it handles 'x' as a logical vector. I added the first line in the
function to convert the logical vector to it's numeric equivalent and
then coerce to character:
bin2dec <- function(x)
{
x <- as.character(as.numeric(x))
b <- as.numeric(unlist(strsplit(x, "")))
pow <- 2 ^ ((length(b) - 1):0)
sum(pow[b == 1])
}
a <- c(TRUE, FALSE, TRUE)
> bin2dec(a)
[1] 5
HTH,
Marc Schwartz
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