[R] Measure the frequencies of pairs in a matrix

[Boris Steipe]

Since order is not important to you, you can order your pairs (e.g. decreasing) before compiling the frequencies.
But I don't understand the second part about values "that do not appear in the matrix". Do you mean you want to assess all combinations? If that's the case I would think about a hash table or other indexed data structure, rather than iterating through a matrix.


B.



On Oct 6, 2015, at 4:59 PM, Hermann Norpois <hnorpois at gmail.com> wrote:

> Hello,
> 
> I have a matrix mat (see dput(mat))
> 
>> mat
>      [,1] [,2]
> [1,]    5    6
> [2,]    6    5
> [3,]    5    4
> [4,]    5    5
> ....
> 
> I want the frequencies of the pairs in a new matrix, whereas the
> combination 5 and 6 is the same as 6 and 5 (see the first two rows of mat).
> In other words: What is the probability of each combination (each row)
> ignoring the order in the combination. As a result I would like to have a
> matrix that includes rows and cols 0, 1, 2 ... max (mat) that do not appear
> in my matrix.
> 
> dput (mat)
> structure(c(5, 6, 5, 5, 4, 3, 6, 7, 4, 7, 5, 5, 5, 5, 6, 5, 5,
> 4, 3, 6, 7, 4, 7, 5, 5, 5, 6, 5, 4, 5, 5, 7, 5, 6, 3, 5, 6, 7,
> 6, 6, 5, 4, 5, 5, 7, 5, 6, 3, 5, 6, 7, 6), .Dim = c(26L, 2L))
> 
> Thanks
> Hermann
> 
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