[R] How to speed up int2bin conversion?

Jeff Newmiller jdnewmil at dcn.davis.ca.us
Thu Dec 1 17:25:34 CET 2011

You might be interested in package "bit".
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Sent from my phone. Please excuse my brevity.

"Jonas Jägermeyr" <jonasjae at pik-potsdam.de> wrote:

>Dear R-help members,
>I'm processing a large amount of MODIS data where quality assessment 
>information is stored as an integer value for each pixel. I have to 
>converted this number to an 8 digit binary flag to get access to the 
>stored quality code (e.g. in2bin(165,8) = 1 0 1 0 0 1 0 1).
>Unfortunately, I did not manage to find a package providing a fast 
>function to do so. I need to run this on millions of pixels and thus 
>wrote the following function.
>int2bin <- function(x,ndigits){
>     base <- array(NA, dim=c(length(x), ndigits))
>     for(q in 1:ndigits){
>           base[, ndigits-q+1] <- (x %% 2)
>           x <- (x %/% 2)
>       }
>     bin<- apply(base,1,paste,collapse="")
>     return(bin)
>Since it is still slow, I have to find a way to express this more 
>elegantly. I'd really appreciate any help.
>Thanking you, with best regards
>Jonas J�germeyr
>Potsdam Institute for Climate Impact Research
>Research Domain II
>	[[alternative HTML version deleted]]
>R-help at r-project.org mailing list
>PLEASE do read the posting guide
>and provide commented, minimal, self-contained, reproducible code.

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