[R] how to get such a subset of a matrix?
Robin Hankin
r.hankin at noc.soton.ac.uk
Fri May 6 15:31:45 CEST 2005
R> a <- matrix(1:36,6,6)
R> is.na(a[row(a)<col(a)]) <- TRUE
R> a
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] 1 NA NA NA NA NA
[2,] 2 8 NA NA NA NA
[3,] 3 9 15 NA NA NA
[4,] 4 10 16 22 NA NA
[5,] 5 11 17 23 29 NA
[6,] 6 12 18 24 30 36
> a[apply(a,1,function(x){sum(is.na(x))<=2}),]
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] 4 10 16 22 NA NA
[2,] 5 11 17 23 29 NA
[3,] 6 12 18 24 30 36
>
Hope this helps
rksh
On May 6, 2005, at 02:21 pm, Xiao Shi wrote:
> Hi everybody,
> Maybe this question is quite simple but i just don't know how to make
> it.
> I have a matrix a somewhat like this one but bigger:
>> a
> f g h i j k
> a NA NA 11 16 21 26
> b NA NA 12 17 22 27
> c NA 8 13 18 23 28
> d NA 9 14 19 24 29
> e NA 10 15 20 25 30
> And i want to get the rows which at most have 2 Na.
> Thanks in advance.
> Shi Jiantao
>
> [[alternative HTML version deleted]]
>
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--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
tel 023-8059-7743
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