I have two matrices, and I need to find if the two-column sets in one matrix appear in the other matrix without regard for the order (A:B = B:A).
As an example, here are two matrices:
X <- matrix(c(23, 33, 4, 21, 5, 27, 47, 39, 37, 8, 30, 42, 59, 63, 53, 50, 49, 65, 53, 59), nrow = 10, ncol = 2, byrow = F)
Y <- matrix(c(30, 21, 53, 23, 63, 37), nrow = 3, ncol = 2, byrow = F)
> X
[,1] [,2]
[1,] 23 30
[2,] 33 42
[3,] 4 59
[4,] 21 63
[5,] 5 53
[6,] 27 50
[7,] 47 49
[8,] 39 65
[9,] 37 53
[10,] 8 59
> Y
[,1] [,2]
[1,] 30 23
[2,] 21 63
[3,] 53 37
I want to be able to find, for example, Y[1,] in X whether it is {30,23} or {23,30}.
I have tried merge
, intersect
, and setdiff
, but none of those will return all the possible matches.
> merge(data.frame(X),data.frame(Y))
X1 X2
1 21 63
> merge(data.frame(Y),data.frame(X))
X1 X2
1 21 63
> intersect(data.frame(X),data.frame(Y))
X1 X2
1 21 63
> intersect(data.frame(Y),data.frame(X))
X1 X2
1 21 63
> setdiff(data.frame(Y),data.frame(X))
X1 X2
1 30 23
2 53 37
> setdiff(data.frame(X),data.frame(Y))
X1 X2
1 23 30
2 33 42
3 4 59
4 5 53
5 27 50
6 47 49
7 39 65
8 37 53
9 8 59
The ultimate goal is to identify the rows in X that contain matches (with or without contents). So, in pseudo-code, it would be:
for each Y[i,] in X
return row number X
We can
sort
by row on each datasetand then do a
match
on thepaste
d rows of each dataset to return the row index of the match