Hi:

Try this:

# Function to generate one sample from the data frame
sampler <- function(df) {
     s1 <- sample(nrow(df), 1, replace = FALSE)
     s2 <- sample(setdiff(1:nrow(df), s1), 2, replace = FALSE)
     list(sample1 = df[s1, grep('^C', names(df))],
          sample2 = df[s2, grep('^W', names(df))])
   }

sampler(mydf)    # try it out on your data frame below

# replicate the process 1000 times
l <- vector('list', 1000)
for(i in seq_along(l)) l[[i]] <- sampler(mydf)

HTH,
Dennis

On Tue, Nov 16, 2010 at 9:53 AM, wangwallace <talenttree@gmail.com> wrote:

>
> Fabulicious!!!!!!!!!!!!!!!!! It worked!!!
>
> One more question, in the following data frame as posted above:
>
>    SubID    CSE1 CSE2 CSE3 CSE4 WSE1 WSE2 WSE3 WSE4
>      1          6      5       6       2      6      2        2       4
>      2          6      4       7       2      6      6        2       3
>      3          5      5       5       5      5      5        4       5
>      4          5      4       3       4      4      4        5       2
>      5          5      6       7       5      6      4        4       1
>      6          5      4       3       6      4      3        7       3
>      7          3      6       6       3      6      5        2       1
>      8          3      6       6       3      6      5        4       7
>
> I want to draw the first random sample consisting of a row of integers
> under
> the first group of variables (CSE1, CSE2, CSE3, CSE4). For example,
> assuming
> the first draw yielded a sample of the first row (6, 5, 6, 2), now I want
> to
> draw another random sample consisting of two rows of integers under the
> second group of variables (WSE1, WSE2, WSE3, WSE4). Also, for the second
> draw, I want to restrict a vector I am going to sample from to only those
> rows that are not correspond to SubID I have sampled. That is, I want to
> sample two rows of integers under the second group of variables (WSE1,
> WSE2,
> WSE3, WSE4) from rows 2, 3, 4, 5, 6, 7, and 8.
>
> Also, I want to repeat this whole process (drawing 1 random row of integers
> under the first group of variables first, AND then another two random rows
> under the second group of variables) for 1000 times. Any ideas? would that
> be possible to do it by just revising the syntax you wrote above? many
> thanks!!!
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Sampling-problem-tp3043804p3045352.html
> Sent from the R help mailing list archive at Nabble.com.
>
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