[R] Matrix and rownames problem

[John Fox]

Dear Patrick,

By default, when indexing returns an array dimension of 1, the corresponding
coordinate is dropped. Try  j <- i[1, 1:2, drop=FALSE], and see ?"[".

I hope this helps,
 John

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Pat Meyer
> Sent: Friday, December 17, 2004 9:34 AM
> To: r-help at stat.math.ethz.ch
> Cc: patrick.meyer at internet.lu
> Subject: [R] Matrix and rownames problem
> 
> Hi,
> I'm quite new to R, so excuse me if this problem has a simple 
> solution.
> 
> I'm working with an array, lets say
> 
> i <- array(c(1:3,3:1), dim=c(3,2))
> 
> Then I want to give the rows and the columns names:
> 
> rownames(i)<-c("a","b","c")
> colnames(i)<-c("d","e")
> 
> The result is given below:
> 
>   d e
> a 1 3
> b 2 2
> c 3 1
> 
> Here comes my problem. When I'm taking a submatrix
> 
> j<-i[1,1:2]
> 
> the result should be (for me) an array of one line, and two 
> colums. Here's the result:
> 
> d e
> 1 3
> 
> When I want to access the rownames of j, it returns NULL. I 
> want it to be "a".
> 
> On the other side, if I take a submatrix 2x2, there is no problem.
> 
> In my problem, rownames(j) must return the name of the 
> extracted row. So I don't understand why a 1x2 array is not a 
> normal array.
> 
> Could someone help me with this?
> 
> Thanx in advance,
> 
> Patrick
> 
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