# [R] Help Help with sampling

Alex99 loyola9988 at yahoo.com
Wed Oct 15 18:32:47 CEST 2008

```Thanks again Jorge,
but when I type in  lapply(res,function(x) rbind(rowMeans(x)) it's like it's
waiting for something else, it doesnt run. I tried "help(lapply)" to learn
more about lappy but didnt give me any result. could you tell me why it
doesnt run and what is lapply for?

Thanks a lot for all your help

Jorge Ivan Velez wrote:
>
> Dear Alex,
> Is this what you want?
>
> X8 X9 X10 X102 X110 X177 X283 X284 X286 X292 X297 X306 X308 X314
> 0  1   0    0    0    1    0    0    0    0    0    0    0    0
> 0  0   0    0    1    0    0    0    0    0    0    0    1    0
> 0  1   0    0    0    0    0    0    0    0    0    0    1    0
> 1  0   0    0    1    0    0    0    0    1    0    0    0
> closeAllConnections()
> rownames(my)=paste('s',1:4,sep="")
>
> # Using 5 samples only
> res=replicate(5,my[,sample(colnames(my),5)],simplify=FALSE)
>
> # mean
> lapply(res,function(x) rbind(rowMeans(x))
>
> # standard deviation
> lapply(res,function(x) apply(x,1,sd,na.rm=TRUE))
>
>
> HTH,
>
> Jorge
>
>
> On Wed, Oct 15, 2008 at 10:58 AM, Alex99 <loyola9988 at yahoo.com> wrote:
>
>>
>> Thanks for the reply Jorge,
>>
>> that works BUT the reason I didn't use it, is because I need to calculate
>> the mean and Standard deviation for S1,S2,S3 and S4 in each sample. which
>> means I'll have 5 means for S1, and 5 means for S2 and 5 means for S3 and
>> 5
>> means for S4 (and at the end I have to get the average of the means for
>> each
>> 'S').
>> I used the following:
>>
>> for(i in 1:5) {temp<-sample(A3,3, replace=F)
>> + Trans=t(temp)
>> + Avg=mean(Trans)
>> + show(temp)
>> + show(Trans)
>> + show(Avg)}
>>
>> the reason I used Transpose is to get the R to give me the mean for S's.
>> but
>> what I get is just one mean for each sample. not the mean for each S.
>> any suggestion how to do it?
>>
>> thanks again for all your help
>>
>> Jorge Ivan Velez wrote:
>> >
>> > Dear Alex,
>> > Is this what you want?
>> >
>> > # Data set
>> > X8 X9 X10 X102 X110 X177 X283 X284 X286 X292 X297 X306 X308 X314
>> > 0  1   0    0    0    1    0    0    0    0    0    0    0    0
>> > 0  0   0    0    1    0    0    0    0    0    0    0    1    0
>> > 0  1   0    0    0    0    0    0    0    0    0    0    1    0
>> > 1  0   0    0    1    0    0    0    0    1    0    0    0
>> > closeAllConnections()
>> > rownames(my)=paste('s',1:4,sep="")
>> >
>> > # Samples
>> > res=list()
>> > for(i in 1:5) res[[i]]<- my[,sample(colnames(my),5)]
>> > res
>> >
>> > HTH,
>> >
>> > Jorge
>> >
>> >
>> > On Wed, Oct 15, 2008 at 10:07 AM, Alex99 <loyola9988 at yahoo.com> wrote:
>> >
>> >>
>> >> Hi everyone,
>> >>
>> >> I have a dataset(named "Mydata") which includes 4 different variables
>> >> named;
>> >> s1,s2,s3,s4 .Each variable(symptom) has 14 patients.
>> >> I need to use random sampling to make, 5 different samples from my
>> data
>> >> with
>> >> 5 patients in each sample. i.e. using all 4 variables I need to make 5
>> >> different samples by changing patients(with 5 patients in each
>> sample).
>> >>
>> >>
>> >>   X8 X9 X10 X102 X110 X177 X283 X284 X286 X292 X297 X306 X308 X314
>> >> s1  0  1   0    0    0    1    0    0    0    0    0    0    0    0
>> >> s2  0  0   0    0    1    0    0    0    0    0    0    0    1    0
>> >> s3  0  1   0    0    0    0    0    0    0    0    0    0    1    0
>> >> s4  1  0   0    0    1    0    0    0    0    1    0    0    0    0
>> >>
>> >>
>> >> I used this code:
>> >>
>> >> temp=list(NULL)
>> >> for(i in 1:5) {temp[i]<-sample(Mydata,5, replace=F)} show(temp)
>> >>
>> >> but I get the following error:
>> >> "number of items to replace is not a multiple of replacement length"
>> >>
>> >> any idea why I get this eeror message and how can I fix it?
>> >> Thanks a lot.
>> >>
>> >> --
>> >> View this message in context:
>> >> http://www.nabble.com/Help-Help-with-sampling-tp19994275p19994275.html
>> >> Sent from the R help mailing list archive at Nabble.com.
>> >>
>> >> ______________________________________________
>> >> R-help at r-project.org mailing list
>> >> https://stat.ethz.ch/mailman/listinfo/r-help
>> >> http://www.R-project.org/posting-guide.html
>> >> and provide commented, minimal, self-contained, reproducible code.
>> >>
>> >
>> >       [[alternative HTML version deleted]]
>> >
>> > ______________________________________________
>> > R-help at r-project.org mailing list
>> > https://stat.ethz.ch/mailman/listinfo/r-help
>> > http://www.R-project.org/posting-guide.html
>> > and provide commented, minimal, self-contained, reproducible code.
>> >
>> >
>>
>> --
>> View this message in context:
>> http://www.nabble.com/Help-Help-with-sampling-tp19994275p19995327.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> 	[[alternative HTML version deleted]]
>
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