On Fri, 2012-01-20 at 18:04 +0100, Martin Batholdy wrote:
> Hi,
>
>
> I am currently trying to z-transform (that is subtracting the mean and divide
> by the standard deviation) multiple columns of a data.frame at the same time.
>
>
> My first approach was:
>
> x <- data.frame(c(0:10), c(10:20))
> (x - colMeans(x)) / apply(x, 2, sd)
>
>
> This is obviously not working.
>
> Is there a convenient way to z-transform each column separately (so in this
> case, each column represents an independent variable that should be
> z-transformed)
?scale
> scale(x)
c.0.10. c.10.20.
[1,] -1.5075567 -1.5075567
[2,] -1.2060454 -1.2060454
[3,] -0.9045340 -0.9045340
[4,] -0.6030227 -0.6030227
[5,] -0.3015113 -0.3015113
[6,] 0.0000000 0.0000000
[7,] 0.3015113 0.3015113
[8,] 0.6030227 0.6030227
[9,] 0.9045340 0.9045340
[10,] 1.2060454 1.2060454
[11,] 1.5075567 1.5075567
attr(,"scaled:center")
c.0.10. c.10.20.
5 15
attr(,"scaled:scale")
c.0.10. c.10.20.
3.316625 3.316625
>
> thanks!
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
Dr. Gavin Simpson [t] +44 (0)20 7679 0522
ECRC, UCL Geography, [f] +44 (0)20 7679 0565
Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk
Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/
UK. WC1E 6BT. [w] http://www.freshwaters.org.uk
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
