[R] Using apply() and scale() in combination
PAlspach at hortresearch.co.nz
Tue May 19 02:25:04 CEST 2009
Tena koe Armin
From the help file of apply():
If each call to 'FUN' returns a vector of length 'n', then 'apply'
returns an array of dimension 'c(n, dim(X)[MARGIN])' if 'n > 1'.
So, one should expect what you got in the second case. You can, of
course, transpose the result using t().
> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] On Behalf Of Armin Raznahan
> Sent: Tuesday, 19 May 2009 9:44 a.m.
> To: r-help at r-project.org
> Subject: [R] Using apply() and scale() in combination
> I am an R newbie, and am coming against a couple of problems
> when I try and apply the scale function across all the rows
> of a matrix.
> #I have a matrix "dt_l".
> > str(dt_l)
> num [1:40962, 1:885] 3.04 4.1 3.4 3.58 3.77 ...
> #I want to convert the values in each row of this matrix into
> standardised values (mean 0, sd 1). I believe the command for
> doing this is "scale()", with the defaults for this function
> being to set mean at 0 and sd at 1.
> Therefore, my desired end-point is an object with the same
> dimensions as dt_l.
> So, I use this command..which I think should applying scale
> to every row of matrix dt_l:
> > dt.stand<-apply(dt_l, 1, scale)
> #This has led to two different sorts of problem:
> (1) On some occasions when I have run the command I get an
> error warning which includes the phrase
> "error: can't allocate region..."
> (2) On other occasions (when as far as I know I have entered
> the same command), it runs. BUT, when I look at the object
> produced the dimensions are different from dt_l ....
> > str(dt.stand_l)
> num [1:885, 1:40962] -0.679 -0.0882 0.1204 1.8571 0.8854 ...
> I would be very grateful for any explanations/fixes that can
> be offered for the above, or any suggestions of alternative
> ways of reaching my desired end-point.
> Yours hopefully
> R-help at r-project.org mailing list
> PLEASE do read the posting guide
> and provide commented, minimal, self-contained, reproducible code.
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