Try this: > sens <- function(ct) { ct[2,2] / sum(ct[,2]) } > spec <- function(ct) { ct[1,1] / sum(ct[,1]) } > > > myt <- matrix( c(1427,271,110,166), ncol=2) > > sens(myt) [1] 0.6014493 > > spec(myt) [1] 0.8404005 >
-Don -- Don MacQueen Lawrence Livermore National Laboratory 7000 East Ave., L-627 Livermore, CA 94550 925-423-1062 On 4/25/14 10:58 AM, "Si Qi L." <liusiqi.n...@gmail.com> wrote: >Hi guys, > >I will be very grateful if you guys can do me a little favor on R. I am >calculating the sensitivity and specificity for a 2*2 matrix, such as > > t > 0 1 > 0 1427 110 > 1 271 166 > > > >My codes are: sens <- function(ct) { ct[2,2] / sum(ct[,2]) } > spec <- function(ct) { ct[1,1] / sum(ct[,1]) } > >But it doesn't show any numerical results. Would you please help me to fix >it? Mnay thanks for your help.:) > >Best regards, > >Siqi > > [[alternative HTML version deleted]] > >______________________________________________ >R-help@r-project.org mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide >http://www.R-project.org/posting-guide.html >and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.