How to get standard deviation of rows in a matrix
On Wed, 9 Mar 2005 13:49:44 -0600
"Jagarlamudi, Choudary" <choudary.jagar at swosu.edu> wrote:
Hi all, I am trying to find sd of my rows in a matrix and i get column sd inspite of extracting rows. I tried to do the sqrt(var(x)) but that did'nt work as well, Here is my data genes 15 24 63 40 25 42 46 35 23 53 37 45 30 37 50 55 40 51 30 48 x<-sd(genes[1:5,]) y<-sqrt(var(genes[1:5,])) I get 4 sds for the 4 columns instead of 5 sds for my 5 rows. Thanks you in advance.
mymat <- matrix(rnorm(20), 5) mymat
[,1] [,2] [,3] [,4] [1,] -0.1418666 -0.6754704 -0.2525154 -1.4832003 [2,] -0.2254920 1.8705093 -0.9678318 -0.1108883 [3,] 2.2501392 0.1687349 -0.1279790 0.7055311 [4,] 0.9893453 -0.5924199 0.2410576 0.9001638 [5,] -0.4179559 0.9334556 -0.6501605 0.6148958
apply(mymat, 1, sd)
[1] 0.6084171 1.2135998 1.0584750 0.7318231 0.7722641 See ?apply HTH, Tobias