# [R] calculating mean for samples

stephen sefick ssefick at gmail.com
Tue Oct 21 14:41:24 CEST 2008

```Yeah, I realized that after the fact, and haven't been able to figure
out how to get it to work  -  The replicate function looks promising,
but i could not get it to work in the couple of minutes that i played
around with it.  I will think about it-  if you figure it out send me
along the solution.

On Tue, Oct 21, 2008 at 8:37 AM, al ex <loyola9988 at yahoo.com> wrote:
> Thanks for the reply Stephen,
> but the samples it makes are all the same:
> " f <- do.call(rbind , rep(A1[sample(nrow(A1), 5),], 5)) " if U print out
> "f", you'll see they are all the same.
>
> --- On Mon, 10/20/08, stephen sefick <ssefick at gmail.com> wrote:
>
> From: stephen sefick <ssefick at gmail.com>
> Subject: Re: [R] calculating mean for samples
> To: loyola9988 at yahoo.com, "R Help" <r-help at r-project.org>
> Date: Monday, October 20, 2008, 12:05 PM
>
> assuming that A1 is the data provided in the first post... it would be
> helpful if you used dput() to copy into an email, so that we could
> just copy the code and data right into a R session and be off and
> running.
>   I hope this helps.
>
> #I used dput() on the object A1
> A1 <- (structure(list(s1 = c(0L, 1L, 0L, 0L, 0L, 1L, 0L, 0L, 0L, 0L),
>     s2 = c(0L, 0L, 0L, 0L, 1L, 0L, 0L, 0L, 0L, 0L), s3 = c(0L,
>     1L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), s4 = c(1L, 0L, 0L, 0L,
>     1L, 0L, 0L, 0L, 0L, 1L)), .Names = c("s1", "s2",
> "s3", "s4"
> ), class = "data.frame", row.names = c(NA, -10L)))
>
> f <- do.call(rbind , rep(A1[sample(nrow(A1), 5),], 5))
> d <- apply(f, MARGIN=1, FUN=mean)
> mean(d[names(d)==s1])
> mean(d[names(d)==s2])
> mean(d[names(d)==s3])
> mean(d[names(d)==s4])
>
> On Mon, Oct 20, 2008 at 2:44 PM, al ex <loyola9988 at yahoo.com> wrote:
>> I dont have a problem with sampling and calculating mean:
>>
>> for(i in 1:5){
>>  res=(A1[sample(nrow(A1), 5),])
>>  Avg=colMeans(res)
>>  STD=sd(res)
>>  print(res)
>>  print(Avg)
>>  print(STD)
>>  }
>>
>> my problem is
>  how to save the mean for each "S" in each sample
> and calculate
>> the grand mean
>>
>>
>>
>> --- On Mon, 10/20/08, stephen sefick <ssefick at gmail.com> wrote:
>>
>> From: stephen sefick <ssefick at gmail.com>
>> Subject: Re: [R] calculating mean for samples
>> To: "Alex99" <loyola9988 at yahoo.com>
>> Date: Monday, October 20, 2008, 11:34 AM
>>
>> look at
>> ?sample
>> ?lapply
>> ?mean
>>
>> On Mon, Oct 20, 2008 at 1:53 PM, Alex99 <loyola9988 at yahoo.com>
> wrote:
>>>
>>>
>>  Hi everyone,
>>>> does any one knows how can I calculate mean for different samples
>>>> i.e. I have a data like this:
>>>>
>>>>  s1 s2 s3 s4
>>>> 1   0  0  0  1
>>>> 2   1  0  1  0
>>>> 3   0  0  0  0
>>>> 4   0  0  0  0
>>>> 5   0  1  0  1
>>>> 6   1
>   0  0  0
>>>> 7   0  0  0  0
>>>> 8   0  0  0  0
>>>> 9   0  0  0  0
>>>> 10  0  0  0  1
>>>>
>>>> I need to make 5 different sample with 5 different persons(rows)
> in
>> each
>>>> sample from it keeping s1,s3,s3,s4 but changing rows. and then
>> calculate
>>>> the mean for each "S" in each sample. and finally
> calculate
>> the grand
>>>> mean,which is the mean of means for each sample. i.e. if I sample
> 5
>> time I
>>>> get 5 different means for s1, s2, s3, s4. then I need to add all
> five
>>>> means for and divide it by 5.(of course I have to do it
>>  for
>> s1,s2,s3,s4
>>>> separately)
>>> --
>>> View this message in context:
>>
> http://www.nabble.com/calculating-mean-for-samples-tp20075174p20075174.html
>>> Sent from the R help mailing list archive at
>  Nabble.com.
>>>
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>>
>>
>>
>> --
>> Stephen Sefick
>> Research Scientist
>>
>> Let's not spend our time and resources thinking about things that are
>> so little or so large that all they really do for us is puff us up and
>> make us feel like gods.  We are mammals, and have not exhausted the
>> annoying little problems of being mammals.
>>
>> 								-K.
>>  Mullis
>>
>> __________________________________________________
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>
>
> --
> Stephen Sefick
> Research Scientist
>
> Let's not spend our time and resources thinking about things that are
> so little or so large that all they really do for us is puff us up and
> make us feel like gods.  We are mammals, and have not exhausted the
> annoying little problems of being mammals.
>
> 								-K. Mullis
>
>

--
Stephen Sefick
Research Scientist