[R] selecting subsets of data from matrix

[Jason Turner]

Laura Quinn wrote:

> Thanks for your help everyone,
> 
> My data is a matrix. However if i use the command:
> 
> x[(x[,20] > 315 | x[,20] < 45), ]
> 
> and then request a summary, I get a warning message saying that a large
> number of the row names have been duplicated - I don't understand this?

If x is the original matrix, and subx is the subseted matrix
(x[(x[,20] > 315 | x[,20] < 45), ])  ...

Do you get this warning message when you type summary(x)?

If you're not explicitly using the rownames for anything other than 
labeling, it can be safely ignored.  Duplicate rownames are a bit 
strange to R, but they're not illegal in matricies.

Cheers

Jason
-- 
Indigo Industrial Controls Ltd.
http://www.indigoindustrial.co.nz
64-21-343-545
jasont at indigoindustrial.co.nz