[R] Converting decimal to binary in R

[Jeff Newmiller]

On Sat, 14 Dec 2013, ???????? wrote:

> i  have write a function to convert decimal number into binary number in R.
>
> dectobin<-function(x){
>  as.numeric(intToBits(x))->x1
>  paste(x1,collapse="")->x2
>  as.numeric(gsub("0+$","",x2))->x3
>  return(as.character(x3))}
>
> dectobin can get right result ,it is so long ,is there a build-in
> function to do ?

I don't know of one. The below function is roughly twice as fast as yours 
and it works on an entire vector of values at once (but it still uses a 
for loop to do so).

decToBinStr <- function(x) {
   l <- floor( log( x, 2 ) ) + 1
   v <- as.logical( intToBits( x ) )
   vc <- rep( "0", length( v ) )
   vc[ v ] <- "1"
   m <- matrix( vc, ncol=length( x ) )
   result <- rep( NA, length( x ) )
   for ( idx in seq.int( length( x ) ) ) {
     result[ idx ] <- paste( m[ seq.int( l[ idx ], 1 ), idx ], collapse="" )
   }
   result
}

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