[R] newbie: remove column with low mean from a matrix

[Tord Snall]

Dear all,

Sorry to bother you with one more newbie question.

I have a dataobject with several hundreds of columns. I want to remove
columns with a mean of the column values below a certain value:

> a<- c(1,2,3,4,5,6)
> b<-c(2,4,6,8,10,12)
> c<- c(3,6,9,12,15,18)
> test<- as.matrix(cbind(a, b, c))
> mean(a)
[1] 3.5
> mean(b)
[1] 7
> mean(c)
[1] 10.5

Say the "certain value" is 5, I would like a new matrix as follows:

> new.test
      b  c
[1,]  2  3
[2,]  4  6
[3,]  6  9
[4,]  8 12
[5,] 10 15
[6,] 12 18


I have searched in the help archive, in help files, and in the
documentation without finding it.


Thanks in advance!

Yours sincerely,
Tord Snäll






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Tord Snäll
Avd. f växtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
Villavägen 14			
SE-752 36 Uppsala, Sweden
Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
E-mail: Tord.Snall at ebc.uu.se
http://www.vaxtbio.uu.se/resfold/snall.htm
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