Re: [R] calculate sd for each row on some columns of a dataframe

Try this: lapply(list(letters[1:3], letters[2:4]), function(x)apply(df[,x], 1, sd)) On 28/02/2008, Albert Vilella <[EMAIL PROTECTED]> wrote: > Hi, > > I've got a dataframe like this: > > df = > data.frame(a=rnorm(100,1),b=rnorm(100,10),c=rnorm(100,100),d=rnorm(100,-100)) > > and I want to cal

[R] calculate sd for each row on some columns of a dataframe

Hi, I've got a dataframe like this: df = data.frame(a=rnorm(100,1),b=rnorm(100,10),c=rnorm(100,100),d=rnorm(100,-100)) and I want to calculate sd1 for (a,b,c) for each entry, and sd2 for (b,c,d) for each entry. I don't seem to find the answer using aggregate or apply, How can I do this? Than