[R] Subset a floating point vector using all.equal?
dwinsemius at comcast.net
Thu May 30 07:37:22 CEST 2013
On May 29, 2013, at 6:27 PM, Peter Lomas wrote:
> I have a whole bunch of data to two decimal places. I've done some
> arithmetic with them, so floating point becomes an issue.
> x <- c(1, 0.15,(0.1+.05),0.4)
> I want to do something like this:
> But you'll notice that is troublesome with the well known floating
> issue. So really I need to do something like this:
> x[all.equal(x, 0.15)]
x[ zapsmall(x-0.15)==0 ]
> But that doesn't work because all.equal wants to compare objects and
> each element.
> I could do:
> x[round(x,2) ==0.15]
> It seems to work in this case, but as I've been working with my data
> concerned its unreliable. What is the most efficient way of
> data using a machine-tolerance equal numeric value?
> Thanks R-Helpers.
David Winsemius, MD
Alameda, CA, USA
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