Turning iteratively all elements after and above a '1' into '0'-s starting from the left bottom corner
1 Ansicht (letzte 30 Tage)
Ältere Kommentare anzeigen
Marin Genov
am 13 Apr. 2022
Kommentiert: Marin Genov
am 13 Apr. 2022
I have logical square matrices consisting of non-intersecting rectangular patches of '1'-s with no gaps and otherwise '0'-s. 'No gaps' in particular means that two different rectangular patches are not allowed to share horizontal or vertical coordinates. Moreover, the rectangular patches are strictly monotone increasing from the POV of the bottom left corner. For example:
A = [0 0 0 0 1;
0 0 0 0 1;
0 1 1 1 0;
0 1 1 1 0;
1 0 0 0 0]
I would like to perform the following operation on A in a fast way, possibly on GPU. Starting from the left bottom corner, I would like to iteratively turn all elements above and after a '1' into '0'. For example:
B = [0 0 0 0 0;
0 0 0 0 1;
0 0 1 0 0;
0 1 0 0 0;
1 0 0 0 0]
That is, B(3,3) = 1 because after the iteration at A(4,2), A(4,3) turns into a '0'.
My logical matrices are of size at most 15 and I would like to perform this operation on a 3D-array of many such square matrices stacked upon each other in a fast way, hence the request for vectorizability if possible.
7 Kommentare
Akzeptierte Antwort
DGM
am 13 Apr. 2022
Bearbeitet: DGM
am 13 Apr. 2022
This might not be particularly efficient, but maybe it's one way (if i'm interpreting it right):
A = [0 0 0 0 0 0 1
0 0 0 0 0 0 1;
0 0 0 0 1 1 0;
0 0 0 0 1 1 0;
0 1 1 1 0 0 0;
0 1 1 1 0 0 0;
1 0 0 0 0 0 0];
D = rot90(hankel(size(A,1):-1:1),2).*A;
D(D==0) = NaN;
Dmin = min(D,[],2);
D = D - (flip(cummax(flip(Dmin)))-1);
output = D==1
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Contour Plots 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!