Count number of column pairs occurrence in 3d array

4 Ansichten (letzte 30 Tage)
Hampus Alfredsson
Hampus Alfredsson am 26 Feb. 2018
I have a 3d array like the example below:
A(:,:,1) = [5.5 2.2; 5.3 2.5; 5.3 2.1; 5.4 2.6]
A(:,:,2) = [5.2 2.9; 5.4 2.6; 5.4 2.6; 5.5 2.2]
I want to calculate the number of occurrences of all column pairs. So for example [5.4 2.6] should equal 3 and [5.5 2.2] should equal 2 while the rest of all pairs will equal 1.
I want the numbers to be stored in a new array at the same location as its representative pair, like this:
B(:,:,1) = [2 1 1 3]
B(:,:,2) = [1 3 3 2]
How can I do this as efficiently as possible? I should add that the real array is much larger so I really need an automated solution.
  2 Kommentare
Jan
Jan am 26 Feb. 2018
Bearbeitet: Jan am 26 Feb. 2018
Do you mean a 2D matrix as output:
B = [2 1 1 3; ...
1 3 3 2]
? Or maybe its transposed?
Hampus Alfredsson
Hampus Alfredsson am 26 Feb. 2018
No, A has "n" different sheets of pairs. I want B to have the same amount of sheets since it sounds simpler to relate between pair and number of occurrences that way. I solved the problem using several nested for-loops, but I feel that there is an easier way to do it.

Melden Sie sich an, um zu kommentieren.

Akzeptierte Antwort

Jan
Jan am 26 Feb. 2018
Bearbeitet: Jan am 26 Feb. 2018
A(:,:,1) = [5.5 2.2; 5.3 2.5; 5.3 2.1; 5.4 2.6];
A(:,:,2) = [5.2 2.9; 5.4 2.6; 5.4 2.6; 5.5 2.2];
[s1, s2, s3] = size(A);
B = reshape(permute(A, [1,3,2]), s1*s3, []);
[C, ~, iB] = unique(B, 'rows', 'stable'); % Find unique pairs
[N, ~, bin] = histcounts(iB,'BinMethod','integers'); % Count the pairs
R = reshape(N(bin), s1, []) % Create output matrix
  1 Kommentar
Hampus Alfredsson
Hampus Alfredsson am 26 Feb. 2018
Good solution @Jan Simon. I might use this depending on how my continued coding turns out. Thank you!

Melden Sie sich an, um zu kommentieren.

Weitere Antworten (0)

Kategorien

Mehr zu Multidimensional Arrays finden Sie in Help Center und File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by