[R] standardize columns selectively within a dataframe

[David Winsemius]

On Sep 1, 2010, at 10:35 AM, Olga Lyashevska wrote:

> Dear all,
>
> I have a dataframe:
> df<-dataframe(a=c(1,2,3),b=c(4,5,6),c=c(7,8,9),d=c(10,11,12))
>
> I want to obtain a new dataframe with columns a and b being  
> standardized
> ((x-mean(x))/sd(x)); the other two columns (c,d) I want to leave
> unchanged. What is the best way to achieve this? I have been trying to
> use subscripts but did not succeed so far.

 > df[ , 1:2] <- scale(df[ , 1:2])
 > df
    a  b c  d
1 -1 -1 7 10
2  0  0 8 11
3  1  1 9 12


-- 

David Winsemius, MD
West Hartford, CT