[R] another basic ?

[Roger Peng]

On Mon, 25 Feb 2002, jimi adams wrote:

> i am sure that there is a simple solution that i am just overlooking, but 
> there is no logical test for =
> there is one for != and >,<, >=, <=...
> what do i do if i need to check if something IS EQUAL

Depends.  To test if two objects are the same, you can use identical().
Or you might use == in other situations.  It's hard to know without more
details.

> or is there an easy way, in working with a matrix of size n x 3,  to sort 
> the matrix by one of the columns?

If m is an n x 3 matrix, to sort by column 1, you could do:

> m.sorted <- m[order(m[,1]), ]

-roger
_______________________________
UCLA Department of Statistics
rpeng at stat.ucla.edu
http://www.stat.ucla.edu/~rpeng

> 
> 
> specifically what i am trying to do is i have a matrix with individual and 
> group labels that is randomly generated, and is by default sorted by the 
> individual labels ( column 1) and i want them to be organized into unique 
> group labels (comlumn 2)
> thanks
> jimi
> jimi adams
> Department of Sociology
> The Ohio State University
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