Moving from an index in the matrix to an x,y value
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Hey
I have a 50x50 matrix that indicates points on the X,Y axis
I have some kind of function that holds the index that indicates a row and a column of some point.
My question is how do I go from an index to get the real value on the X axis and Y axis?
Let's say the indexes I got are:
row_idx=43, col_idx=3
Can I say that the value of the point is (3,7)? Or should we add 1+ to the y value? I got confused..
Thank you
1 Commento
the cyclist
il 19 Gen 2024
I got confused, too.
Maybe you could post a much smaller example (say, 5x5) of your matrix. Then, what is your input, and what should the output be?
Risposte (1)
Star Strider
il 19 Gen 2024
Perhaps something like this —
x = linspace(0, 10, 50);
y = linspace(0, 10, 50);
zm = exp(-(x-4.5).^2/4) .* exp(-(y(:)-4.5).^2/4);
[xm,ym] = ndgrid(x,y);
Zfcn = scatteredInterpolant(xm(:),ym(:),zm(:));
row_idx = 43;
col_idx = 3;
xq = interp1(x, row_idx)
yq = interp1(y, col_idx)
zi = Zfcn(xq,yq);
figure
surf(xm, ym, zm)
hold on
plot3(xq, yq, zi, 'rp', 'MarkerFaceColor','r', 'MarkerSize',15)
hold off
grid on
xlabel('x')
ylabel('y')
zlabel('z')
[az,el] = view
% view(210,el)
.
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