It's a well known quirk of sample that it changes behavior when the x argument
has length 1:
> replicate(10,sample(4:5, 1))
[1] 5 4 5 4 5 4 5 4 4 4
> replicate(10,sample(5:5, 1))
[1] 5 3 1 1 1 2 5 3 2 2
One workaround is to zap the offending branch inside sample:
> Sample <- function (x, size, replace = FALSE, prob = NULL)
x[sample.int(length(x), size, replace, prob)]
> replicate(10,Sample(5:5, 1))
[1] 5 5 5 5 5 5 5 5 5 5
(It's one of the cases of misguided user-friendliness that is probably long
regretted by its authors, but has been around for so long that it is painful to
change because code relies on the current behavior. A similar case is diag().)
-pd
On 22 May 2014, at 11:05 , Jim Lemon <j...@bitwrit.com.au> wrote:
> On Thu, 22 May 2014 09:54:13 AM Ragia Ibrahim wrote:
>> Hi,
>> kindly I want to select randomly and item from list of items. the list
>> generated in a looping process. I used sample(mylist,1) it works fine.
>> BUTsome times the list have only one item. that should be chosen in
> this
>> case since there is no other one. I found that sample return different
> item
>> not included in the list thanks in advance
>> RAE
>>
> Hi RAE,
> This doesn't happen in an example like this:
>
> for(i in 1:5) {
> testlist<-list()
> for(j in 1:i) testlist[[j]]<-sample(LETTERS[1:26],1)
> cat("list is\n")
> print(testlist)
> cat("sample is\n")
> print(sample(testlist,1))
> }
>
> How are you generating your lists?
>
> Jim
>
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--
Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: pda...@gmail.com
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