Find center of mass of parts of a matrix
23 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Hi, Let us say that I have a matrix as shown below:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/158429/image.png)
Then I apply a treshold to this matrix and am left with a region of interest. As such:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/158431/image.png)
How can I find the center of mass for this region of interest (using values from the corresponding indexes in the first matrix) and the location of this center of mass in the original matrix?
Thanks for any help
0 Kommentare
Akzeptierte Antwort
Guillaume
am 28 Nov. 2016
Bearbeitet: Guillaume
am 28 Nov. 2016
Well, go back to the definition of the centre of mass, which is just a weighted mean:
%inputs:
%originalmatrix: the original matrix
%binarisedmatrix = originalmatrix > threshold; %the thresholded matrix, a logical array
[rows, cols] = ndgrid(1:size(originalmatrix, 1), 1:size(originalmatrix, 2));
rowcentre = sum(rows(binarisedmatrix) .* originalmatrix(binarisedmatrix)) / sum(originalmatrix(binarisedmatrix));
colcentre = sum(cols(binarisedmatrix) .* originalmatrix(binarisedmatrix)) / sum(originalmatrix(binarisedmatrix));
4 Kommentare
Guillaume
am 28 Nov. 2016
Works fine for me:
originalmatrix = ones(10);
originalmatrix(4:7, 4:7) = 2 %semicolon missing for display
binarisedmatrix = originalmatrix > 1 %semicolon missing for display
[rows, cols] = ndgrid(1:size(originalmatrix, 1), 1:size(originalmatrix, 2));
rowcentre = sum(rows(binarisedmatrix) .* originalmatrix(binarisedmatrix)) / sum(originalmatrix(binarisedmatrix)) %semicolon missing for display
colcentre = sum(cols(binarisedmatrix) .* originalmatrix(binarisedmatrix)) / sum(originalmatrix(binarisedmatrix)) %semicolon missing for display
returns 5.5 for both rowcentre and colcentre
Weitere Antworten (1)
Siehe auch
Kategorien
Mehr zu Logical 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!