Hi Dennis! Here is a possible solution to consider:
a <- data.frame(x=1:25,y=rnorm(25)) a
x y 1 1 1.38958705 2 2 -0.45165628 3 3 0.86517671 4 4 0.40802481 5 5 -2.00104605 6 6 0.11152748 7 7 1.84400316 8 8 0.80775204 9 9 -0.12510867 10 10 -0.13650037 11 11 -0.63498148 12 12 1.70665004 13 13 -0.42427846 14 14 0.38587832 15 15 -0.07601500 16 16 0.40442795 17 17 1.78181958 18 18 -0.07199413 19 19 -0.62582419 20 20 0.71653130 21 21 -1.07557102 22 22 -0.04874676 23 23 -0.09447060 24 24 -0.99221486 25 25 0.16559026
# Set row numbers.... b <- c(2,5,7,18,22) a[b,2] <- rnorm(length(b)) a
x y 1 1 1.3895870 2 2 -0.4613160 3 3 0.8651767 4 4 0.4080248 5 5 -0.5564420 6 6 0.1115275 7 7 1.6625939 8 8 0.8077520 9 9 -0.1251087 10 10 -0.1365004 11 11 -0.6349815 12 12 1.7066500 13 13 -0.4242785 14 14 0.3858783 15 15 -0.0760150 16 16 0.4044279 17 17 1.7818196 18 18 2.0357456 19 19 -0.6258242 20 20 0.7165313 21 21 -1.0755710 22 22 -1.2000225 23 23 -0.0944706 24 24 -0.9922149 25 25 0.1655903 Hope this can be useful! Note: I accidentally deleted the original e-mail. Sincerely, Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: hodgess at gator.uhd.edu