[R] checking for identical columns in a mxn matrix

[Liaw, Andy]

> From: Rajarshi Guha

> On Wed, 2003-12-03 at 13:18, J.R. Lockwood wrote:
> 
> > list will come up with something clever.  the other issues 
> is that you
> > need to be careful when doing equality comparisons with 
> floating point
> > numbers.  unless your matrix consists of characters or integers,
> > you'll need to think about some level of numerical tolerance of your
> > comparison.
> 
> Yes, the matrix will always be integer.

Other than what J.R. and Marc suggested, you might could try to use

dist(t(x), method="manhattan")

and see which entries are 0 (or close enough to 0).

HTH,
Andy


 
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