Finding the highest mountain peak
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Brantosaurus
am 29 Sep. 2022
Kommentiert: Brantosaurus
am 30 Sep. 2022
How might i find the highest mountain peak, and its name, from a defined set of named mountains?
I have data for a set of 10 mountains as 4 matrices.
[X] and [Y] are single row and column matrices defining distances along orthogonal horizontal coordinates.
[Z] is a 3D matrix (:,:,i) containing corresponding x,y height values and an index i=1:10 to define the mountain set.
[Name] is a 10 element 1D text matrix of of the mountain names.
Using a for loop I can plot the surfaces, find the peaks of each mountain and their names:
surf(X,Y,Z(:,:,i))
maximum=max(max(Z(:,:,i)))
Name(i)
How might i find the overall highest peak, and its name in one hit (without the loop)?
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Akzeptierte Antwort
Image Analyst
am 29 Sep. 2022
Why can't you just do this to find the row and column of the max for each of the 10 slices of data:
for k = 1 : size(Z, 3)
% Extract this mountain set.
thisMountainSet = Z(:, :, k);
% Find the max value of it
maxValue(k) = max(thisMountainSet(:));
% Find row(s) and column(s) where it occurs.
[rowsOfMax, colsOfMax] = find(thisMountainSet == maxValue(k));
% Now do something with this information....
end
3 Kommentare
Image Analyst
am 30 Sep. 2022
Personally I prefer using find() to get the rows and columns directly and immediately rather than using the confusing, intermediate function ind2sub(). Note also about the solution you accepted, max only gives you one max location (if you ask for the index), not all of them like find() does, so it your max occurs in more than one location, you may want to know that, and max won't tell you that.
Weitere Antworten (2)
KSSV
am 29 Sep. 2022
Bearbeitet: KSSV
am 29 Sep. 2022
[val,idx] = max(Z,[],3) ;
Get the maximum along third dimension, idx gives you the thirs index where max occurs. Now find the max of val, get it's index.
Or you ccan also use.
A = rand(3,3,3);
[M,I] = max(A(:));
[I_row, I_col, I_page] = ind2sub(size(A),I)
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