[R] Odp: Sampling question

[Petr PIKAL]

Hi

It is rather unclear how do you want sample your data. It seems to me that 
you can  sample row numbers and choose sampled rows from data frame.

I probably direct output to a list ("mylist") and use

result <- lapply("mylist", GFD)

Regards
Petr



r-help-bounces at r-project.org napsal dne 17.01.2011 16:31:59:

> Dear list i have a sample question
> 
> I have a dataframe of 1500 species and 13 life history traits. 
> 
> small example code:
> 
> traits <- data.frame(letters[1:9],
>        sample(letters, 9),
>        sample(letters, 9),
>        sample(letters, 9),
>        sample(letters, 9),
>        sample(letters, 9),
>        sample(letters, 9),
>        sample(letters, 9),
>        sample(letters, 9))
> colnames(traits) <- c("species", 1:8)
> 
> What i want to do is:
> 
> Sample a number of species from the data frame in integers of 50: -  50 
> species, 100 species ,150,200... up-to 1500, when i sample them i also 
want 
> the traits associated with them to be kept intact. For each species 
number i 
> would like a 1000 repetitions. So i would like 50 species with their 
life 
> history traits randomly sampled 1000 times, then 100 species with their 
life 
> history traits sampled 1000 times. I appreciate that as i get to the 
higher 
> numbers i.e 1500 species this will only be sampled once, therefore i 
will need
> to use replace = yes.
> 
> Then i have a function i want to run on the sample so for the 50 species 
 i 
> want to run a function which requires the name of the sample
> 
> GFD(50species_sample1)
> GFD(50species_sample2) etc to 
> GFD(50species_sample1000)
> 
> Then 
> 
> GFD(100species_sample1)
> 
> etc.
> With the reults put into a data-frame.
> 
> I am relatively new to R, i could probably hack together a code but i am 

> unsure how to join it up so i sample, retain the data and then use it in 
a function?
> 
> Any help would be greatly appreciated.
> 
> I appreciate this is a lot to ask so any help would be greatly 
appreciated.
> 
> Thanks in advance,
> 
> Chris
> 
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