Hi:
The deal with replicate() is that its second argument is a *function*; more
specifically, a function *call*. That's why Henrique's solution worked and
your attempt didn't. Inside replicate(), if the function has arguments, they
need to be supplied. This works:
testdat <- function(df, n) df[sample(nrow(df), n, replace = TRUE), ] #
function definition
replicate(3, testdat(growth, 12), simplify = FALSE)
^^^^^^^^^^^^^^^^^^^
function call
The argument simplify = FALSE means that replicate will not try to simplify
the output from the function.
I called your growth data fd, so
> replicate(3, testdat(fd, 12), simplify = FALSE)
[[1]]
Age Length
7 4 399
8 1 120
6 5 453
1 2 200
2 5 450
5 8 798
9 2 202
2.1 5 450
7.1 4 399
6.1 5 453
7.2 4 399
6.2 5 453
[[2]]
Age Length
9 2 202
5 8 798
6 5 453
9.1 2 202
9.2 2 202
5.1 8 798
3 6 600
1 2 200
8 1 120
2 5 450
5.2 8 798
9.3 2 202
[[3]]
Age Length
3 6 600
3.1 6 600
9 2 202
7 4 399
5 8 798
1 2 200
4 7 702
6 5 453
5.1 8 798
5.2 8 798
2 5 450
9.1 2 202
The function is defined a little more generally so that you can control the
sample size.
HTH,
Dennis
On Wed, Sep 29, 2010 at 11:19 AM, Michael Larkin <mlar...@rsmas.miami.edu>wrote:
> I am trying to get R to resample my dataset of two columns of age and
> length
> data for fish. I got it to work, but it is not resampling every replicate.
> Instead, it resamples my data once and then repeated it 5 times.
>
> Here is my dataset of 9 fish samples with an age and length for each one:
> Age Length
> 2 200
> 5 450
> 6 600
> 7 702
> 8 798
> 5 453
> 4 399
> 1 120
> 2 202
>
>
> Here is my code which resamples my data to produce up to 9 different
> samples
> and creates a new dataset of 12 samples:
>
> testdat<-growth[sample(9,12,replace=T),]
>
>
> Now I want R to repeat this procedure 5 times. Here is my code:
>
>
> testdat2 <- replicate(5, sample(testdat), simplify=F)
> testdat2
>
> Here is my output showing that it did it once and then just repeated the
> values:
>
>
> > testdat2
> [[1]]
> Age Length
> 1 2 200
> 9 2 202
> 8 1 120
> 5 8 798
> 4 7 702
> 6 5 453
> 1.1 2 200
> 4.1 7 702
> 4.2 7 702
> 5.1 8 798
> 4.3 7 702
> 6.1 5 453
>
> [[2]]
> Age Length
> 1 2 200
> 9 2 202
> 8 1 120
> 5 8 798
> 4 7 702
> 6 5 453
> 1.1 2 200
> 4.1 7 702
> 4.2 7 702
> 5.1 8 798
> 4.3 7 702
> 6.1 5 453
>
> [[3]]
> Age Length
> 1 2 200
> 9 2 202
> 8 1 120
> 5 8 798
> 4 7 702
> 6 5 453
> 1.1 2 200
> 4.1 7 702
> 4.2 7 702
> 5.1 8 798
> 4.3 7 702
> 6.1 5 453
>
> [[4]]
> Length Age
> 1 200 2
> 9 202 2
> 8 120 1
> 5 798 8
> 4 702 7
> 6 453 5
> 1.1 200 2
> 4.1 702 7
> 4.2 702 7
> 5.1 798 8
> 4.3 702 7
> 6.1 453 5
>
> [[5]]
> Length Age
> 1 200 2
> 9 202 2
> 8 120 1
> 5 798 8
> 4 702 7
> 6 453 5
> 1.1 200 2
> 4.1 702 7
> 4.2 702 7
> 5.1 798 8
> 4.3 702 7
> 6.1 453 5
>
>
> Any advice on how to get R to resample each time would be greatly
> appreciated?
>
> Mike
>
> ______________________________________________
> R-help@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.
>
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