bit set or bit test
Hi Mike, I'm not sure I understand your message, but see if this example is useful. ntharray <- rbind(c(1,0,0,1,0),c(0,0,1,0,1)) ntharray%*%2^(0:(ncol(ntharray)-1)) # [,1] #[1,] 9 #[2,] 20 See also ?binary in package "wle". library(wle) binary(9,dim=5) #$binary #[1] 1 0 0 1 0 # #$dicotomy #[1] TRUE FALSE FALSE TRUE FALSE HTH, Jerome
On April 16, 2003 11:45 pm, Mike Sumner wrote:
Hello, does R have functions for setting and testing bit values? I want to conserve memory for storing presence/absence data for large multiple arrays within a single array, using element values like present[x,y] <- ntharray[x,y]*(2^n) where presence is 1, non-presence is 0 and n is the nth array e.g. 1*(2^0) + 0*(2^1) + 0*(2^2) + 1*(2^3) + 0(2^4) for storing the value 9 for presence in the first and fourth array, and absence in the second, third and fifth arrays. Does R already have something to handle stuff like this? Cheers, Mike.
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Jerome Asselin (J?r?me), Statistical Analyst British Columbia Centre for Excellence in HIV/AIDS St. Paul's Hospital, 608 - 1081 Burrard Street Vancouver, British Columbia, CANADA V6Z 1Y6 Email: jerome at hivnet.ubc.ca Phone: 604 806-9112 Fax: 604 806-9044