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

[Henrique Dallazuanna]

Try this:

lapply(list(letters[1:3], letters[2:4]), function(x)apply(df[,x], 1, sd))

On 28/02/2008, Albert Vilella <avilella at gmail.com> 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 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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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O