Thanks to Jay Kerns and Jim Lemon for their help. It's exactly what I wanted
and "aggregate" is very efficient even with a huge data. Thanks
"G. Jay Kerns" <gkerns@ysu.edu> a écrit : Hi Louis,
If I am understanding your question correctly, here is one way:
suppose your matrix is M of dimension n x k.
D <- data.frame(M) # convert to data frame
ones <- rep(1, n) # a column of 1s
Now you can count the number of repeats of each unique row.
aggregate( ones, by = as.list(D), FUN = sum)
The output will be a data frame with the unique rows, and a column at
the end labeled "x" with the frequency of each unique row.
Once you get this you can convert to a list, manipulate, etc. I am
sure that there exist faster/better methods.
Best,
Jay
On Dec 21, 2007 5:03 PM, Louis Martin wrote:> Hi,
>
> I have a matrix of duplicate rows. How to output a list the unique rows
with their count? I have used "unique" to have the unique rows, but
can't produce the occurences of each unique row.
>
> Thanks
>
> Louis
>
>
>
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G. Jay Kerns, Ph.D.
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Department of Mathematics & Statistics
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