R help - Jan 2011 - Sampling question

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

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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