On May 17, 2012, at 6:45 AM, Axel Urbiz wrote:
Dear List,
Is there a way I can sort a sample based on a sort index constructed
from
the data from which the sample is taken? Basically, I need to take
'many'
samples from the same source data and sort them. This can be very time
consuming for long vectors. Is there any way I can sort the data
only once
initially, and use that sort order for the samples?
I believe that idea is what is implemented in tree-based
classifiers, so
the data is sorted only once initially and that sort order is used
for the
child nodes.
set.seed(12345)
x <- sample(0:100, 10)
x.order <- order(x)
x.sorted <- x[x.order]
sample.ind <- sample(1:length(x), 5, replace = TRUE) #sample 1/2
size with
replacement
x.sample <- x[sample.ind]
x.sample.sorted <- #??? (without sorting again)
Thanks for any help on this.
If you had created a named vector or used a dataframe with rownames
you would have a record of the original sort order.
Regards,
Axel.
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