[R] calculating mean excluding zeros

[Bert Gunter]

Sarah et. al:

On Tue, Jul 19, 2011 at 1:56 PM, Sarah Goslee <sarah.goslee at gmail.com> wrote:
> In the more general case, that approach is prone to machine precision
> error (FAQ 7.31).
>
> Here's a clunky but safer alternative:
>
Perhaps ?zapsmall  .

However, I would agree with your sentiments that it may depend on
context. Finite precision can be a tricky thing.

-- Bert


>> 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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-- 
"Men by nature long to get on to the ultimate truths, and will often
be impatient with elementary studies or fight shy of them. If it were
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-- Maimonides (1135-1204)

Bert Gunter
Genentech Nonclinical Biostatistics