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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