R help - Sep 2010 - repeat a function

I have R randomly sampling my array made up of 2 columns of data.  Here is
my code randomly sampling 5 different rows from my dataset to create a new
dataset of 8 rows of data:    

 

testdat<-growth[sample(5,8,replace=T),]

 

Now I want to tell R to repeat this function 50 times and give me the
output.  I have been searching the internet and have been unable to figure
this out.  Any advice would be greatly appreciated.  

 

Mike


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Hi Michael

testdat <- replicate( 50, growth[ sample(nrow(growth), 8, rep=TRUE) ] )

testdat will then be a matrix of 8 x 50 = 400 rows where each lot of 8
is a sample.

Alternatively you can do...
testdat <- replicate( 50, growth[ sample(nrow(growth), 8, rep=TRUE) ],
simplify=FALSE )

Now testdat will be a list of 50 elements, each of which is a sample matrix

Michael

On 29 September 2010 13:49, Michael Larkin <mlarkin at rsmas.miami.edu>
wrote:
> I have R randomly sampling my array made up of 2 columns of data. ?Here is
> my code randomly sampling 5 different rows from my dataset to create a new
> dataset of 8 rows of data:
>
>
>
> testdat<-growth[sample(5,8,replace=T),]
>
>
>
> Now I want to tell R to repeat this function 50 times and give me the
> output. ?I have been searching the internet and have been unable to figure
> this out. ?Any advice would be greatly appreciated.
>
>
>
> Mike
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

On 30 September 2010 02:48, Michael Larkin <mlarkin at rsmas.miami.edu>
wrote:
> >
> > testdat <- replicate( 50, growth[ sample(nrow(growth), 8, rep=TRUE)
] )
>
> I can't seem to get it to work. ?I keep getting the error message of
> "undefined columns selected"
>
> Any advice?
I'd need to know the dimensions of your matrix / data.frame and see
the command that you're using to offer any useful advice.

Michael