[R] sample {base}

[Sarah Goslee]

What about using instead
size = min(5, length(Gpool$SampleNb[Gpool$LngtClas == LngtClas[[4]] &
Gpool$SpCode == SpCode[[2]]])

that would make sure your sample is either the size of the data or 5.

Sarah

On Wed, Jun 5, 2013 at 10:27 AM, Xochitl CORMON
<Xochitl.Cormon at ifremer.fr> wrote:
> Hi all,
>
> I'm trying to randomly select sample numbers for length class groups (5 per
> length class).
>
> For this I'm using a loop FOR and the function sample () and specified a
> size for the sampling of 5. Unfortunately, one of the length class group
> does not contain 5 individuals. For me is not a big deal as I have others
> groups to complete. However it bothers me that the sampling function does
> not select any individuals in this group generating the error below :
>
> Error in sample(Gpool2$SampleNb[Gpool2$LngtClas == LngtClas[[i]] &
> Gpool2$SpCode ==  : can not take a sample larger than the population when
> 'replace = FALSE'.
>
> I understand why this error message appears but I was wondering if there is
> a way to select all the items present in the group even if it's not 5
> (something like size =< 5).
>
> LngtClas <- list( "40_49", "50_59", "60_69", "70_")
> SpCode <- list ("POLLVIR ", "MERLMER")
>
> a <- as.character(sample(Gpool$SampleNb[Gpool$LngtClas == LngtClas[[4]] &
> Gpool$SpCode == SpCode[[2]]], size = 5, replace = FALSE))
>
> You can find enclosed my dataset,
>
> Thank you for the help,
>
> Xochitl C.

-- 
Sarah Goslee
http://www.functionaldiversity.org