[R] How to detect if a vector is FP constant?

[Albyn Jones]

how about 

           all.equal(x,rep(mean(x),length(x)))
or

           all.equal(x,rep(mean(x),length(x), tolerance=...)

albyn

On Mon, Nov 08, 2010 at 06:45:00PM -0600, Hadley Wickham wrote:
> Hi all,
> 
> What's the equivalent to length(unique(x)) == 1 if want to ignore
> small floating point differences?  Should I look at diff(range(x)) or
> sd(x) or something else?  What cut off should I use?
> 
> If it helps to be explicit, I'm interested in detecting when a vector
> is constant for the purpose of visual display.  In other words, if I
> rescale x to [0, 1] do I have enough precision to get at least 100
> unique values.
> 
> Thanks!
> 
> Hadley
> 
> -- 
> Assistant Professor / Dobelman Family Junior Chair
> Department of Statistics / Rice University
> http://had.co.nz/
> 
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-- 
Albyn Jones
Reed College
jones at reed.edu