Try this:

subset(merge(X, Y, by.x = 'groups', by.y = 1, all = TRUE), values < V2, -V2)


On Wed, Oct 20, 2010 at 1:37 PM, swam <sundarswam@yahoo.com> wrote:

>
> I am needing some help in removing certain rows in a data.matrix and then
> do
> some calculation. So Iam need to removing certain values above a threshold
> or value from another  vector.
>
> For eg.. in the below data matrix X there are 6 groups (A, B, C, D, E ,F)
>
> >X
> rows    groups  values
> 1       A       1.2
> 2       A       0.2
> 3       A       6
> 4       A       0.5
> 5       A       22
> 6       B       0.2
> 7       B       1
> 8       C       0.5
> 9       D       5
> 10      D       4
> 11      D       40
> 12      E       0.3
> 13      E       0.5
> 14      E       1
> 15      E       1.1
> 16      E       0.9
> 17      E       4
> 18      F       0.22
> 19      F       0.32
> 20      F       1.5
>
>
> I have another array  Y with 6 values (equal to the number of groups in X).
> I need to remove the rows in each group in X that is greater than the first
> value in Y for Group A in X and similarly for group B and so on…..
>
> >Y
>
>
> A       1.5
> B       1.1
> C       0.8
> D       6
> E       2
> F       1.9
>
>
> For eg… any value greater than 1.5 (from vector Y) must be removed in
> Matrix
> X  only for group A. similarly for all, hence the result will be like the
> matrix shown below…
>
> rows    groups  values
> 1       A       1.2
> 2       A       0.2
> 3       A       6
> 4       A       0.5
> 5       B       0.2
> 6       B       1
> 7       C       0.5
> 8       D       5
> 9       D       4
> 10      E       0.3
> 11      E       0.5
> 12      E       1
> 13      E       1.1
> 14      E       0.9
> 15      F       0.22
> 16      F       0.32
> 17      F       1.5
>
>
> I tried to get this with no luck any help would be appreciated.
>
> swam
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/removing-rows-from-a-matrix-using-condition-within-groups-tp3004132p3004132.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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