In order to use stratified sampling, either try to implement it yourself
or use the "sampling" package and its function strata() as in:
s1 <- strata(cc, stratanames="ID", size=rep(1, 20),
method="srswr")
then you will get 1 observation for each ID. Note that it is not
important to use "with replacement" in your case, since you only
sample
1 obervation for each stratum.
Uwe Ligges
Krystyna Golabek wrote:> Dear R-users
>
> I have a dataset of 243 lines with replicate information for 20 different
individuals (ID).
> I would like to randomly sample this dataset 100 times with a selection of
unique IDs in each sample.
>
> First to create a random sample I have;
>
> cc<-read.table(blah.blah.blah)
> names(cc)
> [1] "CALL" "CONTEXT" "ORDER"
"ID" "STATUS"
>
> s1<-cc[sample(1:243,20,replace=TRUE),]
>
> This code samples 20 rows from the dataset but can anyone help me write the
code to request unique(ID) in this sample?
>
> Thank you so much for your time and help.
>
> Krystyna Golabek
>
>
>
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