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

From: Albert Vilella <avilella_at_gmail.com>
Date: Thu, 28 Feb 2008 11:27:51 +0000


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?

Thanks in advance,

Cheers,

    Albert.



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