[R] Odp: Looping through all possible combinations of cases
Petr PIKAL
petr.pikal at precheza.cz
Mon Jul 30 16:02:16 CEST 2007
Hi
I am not sure about using loops but something like
colSums(combn(DATA[,1],2))
gives you sums of all pairs and
colSums(combn(DATA[,1],3))
sums of all triplets
etc.
if you want to know which ones they are just use combn on names.
e.g.
> y
X1.5
a 1
b 2
c 3
d 4
e 5
> colSums(combn(y[,1],2))
[1] 3 4 5 6 5 6 7 7 8 9
> combn(row.names(y),2)
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] "a" "a" "a" "a" "b" "b" "b" "c" "c" "d"
[2,] "b" "c" "d" "e" "c" "d" "e" "d" "e" "e"
Regards
Petr
r-help-bounces at stat.math.ethz.ch napsal dne 27.07.2007 20:35:39:
> Hello!
>
> I have a regular data frame (DATA) with 10 people and 1 column
> ('variable'). Its cases are people with names ('a', 'b', 'c', 'd',
> 'e', 'f', etc.). I would like to write a function that would sum up
> the values on 'variable' of all possible combinations of people, i.e.
>
> 1. I would like to write a loop - in such a way that it loops through
> each possible pair of cases (i.e., ab, ac, ad, etc.) and sums up their
> respective values on 'variable'
>
> 2. I would like to write a loop - in such a way that it loops through
> each possible trio of cases (i.e., abc, abd, abe, etc.) and sums up
> their respective values on 'variable'.
>
> 3. I would like to write a loop - in such a way that it loops through
> each possible quartet of cases (i.e., abcd, abce, abcf, etc.) and sums
> up their respective values on 'variable'.
>
> etc.
>
> Then, at the end I want to capture all possible combinations that were
> considered (i.e., what elements were combined in it) and get the value
> of the sum for each combination.
>
> How should I do it?
> Thanks a lot!
> Dimitri
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
More information about the R-help
mailing list