On Nov 13, 2009, at 7:46 PM, Jorge Ivan Velez wrote:

Hi Rachel,

Here is a suggestion:

index <- sample(100)
mysample <- gly[index, ]
mysample


I doubt that was what he was hoping to get (which would be a permutation of 1:100 rather than a subsample).

try:
samp <- gly[ sample(nrow(gly), 100), ]

--
David

See ?sample for more information.

HTH,
Jorge


On Fri, Nov 13, 2009 at 5:20 PM, Hayes, Rachel M <> wrote:

Hi All,



I want to take a simple random sample from a large dataset, gly, but I'm
getting an error message.  Any help?



dim(gly)

[1] 112371     37

s1 <- sample(gly,100)

Error in `[.data.frame`(x, .Internal(sample(length(x), size, replace, :


cannot take a sample larger than the population when 'replace = FALSE'

It is not a misleading error once you consider that the length of a data.frame, which is what you handed to sample(), is the number of columns rather than the number of rows. Data.frames are lists.

--

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

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