[R] calculating mean excluding zeros
Sarah Goslee
sarah.goslee at gmail.com
Tue Jul 19 22:56:01 CEST 2011
In the more general case, that approach is prone to machine precision
error (FAQ 7.31).
Here's a clunky but safer alternative:
> set.seed(1234)
> testvec <- sample(0:10, 100, replace=TRUE)
> mean(testvec)
[1] 4.31
> mean(testvec[testvec != 0])
[1] 4.842697
> mean(testvec[!sapply(testvec, function(x)isTRUE(all.equal(x, 0)))])
[1] 4.842697
>
(Is there an elementwise equivalent to all.equal() that I'm missing?)
Sarah
On Tue, Jul 19, 2011 at 4:48 PM, Weidong Gu <anopheles123 at gmail.com> wrote:
> You can do it by subsetting or indexing
>
> r<-c(0,0,0,rnorm(10,10,5))
>> mean(r)
> [1] 8.052215
>> mean(r[r!=0])
> [1] 10.46788
>
> Weidong Gu
>
> On Tue, Jul 19, 2011 at 4:36 PM, Dimitri Liakhovitski
> <dimitri.liakhovitski at gmail.com> wrote:
>> Sorry if it's been discussed before - don't seem to find it.
>> I'd like to calculate a mean while ignoring zeros.
>> "mean" doesn't seem to have an option for that.
>> Any other function/package that could do it?
>>
>> Thanks for a pointer!
>>
>> --
>> Dimitri Liakhovitski
>> marketfusionanalytics.com
>>
--
Sarah Goslee
http://www.functionaldiversity.org
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