[R] how do I extract all possible combinations of rows from a column
arun
smartpink111 at yahoo.com
Tue Jan 21 21:57:49 CET 2014
Hi,
May be this helps:
library(gtools)
as.data.frame(t(combinations(5,3,1:5)))
# V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
#1 1 1 1 1 1 1 2 2 2 3
#2 2 2 2 3 3 4 3 3 4 4
#3 3 4 5 4 5 5 4 5 5 5
A.K.
For a column of data, I need to extract all possible unique
combinations of 3 rows and combine the results into a data frame (as
columns). So, for example, if I had a column called "test" that had five rows (the contents of which were the numbers 1:5) all possible
combinations of 3 rows would be
1,2,3
1,2,4
1,2,5
1,3,4
1,3,5
1,4,5
2,3,4
2,4,5
2,4,5
3,4,5
So for this example, R would extract all the combinations shown, and I would get a data frame that looked like this
1 1 1 1 1 1 2 2 2 3
2 2 2 3 3 4 3 3 4 4
3 4 5 4 5 5 4 5 5 5
Note: I am not considering rearrangements of the same three rows
to be unique. In other words, the combinations 123, 132, 213, 231, 312,
321 are all the same as far as I am concerned. If it is not possible to
do it that way, it will still be helpful, but not quite as helpful.
Thanks for the help!
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