quantaize data and build an histogram

1 次查看(过去 30 天)
michael
michael 2021-10-29
回答: Ganesh 2024-6-14
Hello,
I have a 3D data (X,Y,Z). Where X is between 0 to 360, Y is between 0 to 180 and Z is between -100 to + 100.
I'd like to quantize the data to NxM scale values on X and Y axes respectively and to have some mean value for Z.
This data shall be displayed on 2D plot where the Z values shall be represented by colors (if value is close to 100, then green, if the value is close to -100 then red).
How this could be done?

回答(1 个)

Ganesh
Ganesh 2024-6-14
You can use the following code to achieve what you are trying to do:
X = randi([0, 360], 1000, 1);
Y = randi([0, 180], 1000, 1);
Z = randi([-100, 100], 1000, 1);
Nx = 36;
M = 18;
edgesX = linspace(0, 360, Nx+1);
edgesY = linspace(0, 180, M+1);
quantizedX = discretize(X, edgesX);
quantizedY = discretize(Y, edgesY);
uniquePairs = unique([quantizedX, quantizedY], 'rows');
meanZ = zeros(size(uniquePairs, 1), 1);
for i = 1:size(uniquePairs, 1)
idx = quantizedX == uniquePairs(i, 1) & quantizedY == uniquePairs(i, 2);
meanZ(i) = mean(Z(idx));
end
Zgrid = nan(Nx, M);
for i = 1:size(uniquePairs, 1)
Zgrid(uniquePairs(i, 1), uniquePairs(i, 2)) = meanZ(i);
end
figure;
imagesc(Zgrid);
colorbar;
colormap([linspace(1,0,256)', linspace(0,1,256)', zeros(256,1)]);
caxis([-100 100]);
xlabel('Quantized X');
ylabel('Quantized Y');
title('Mean Z Values Represented by Color');
axis xy;
Here, we primarily make use of the "discretize()" function to divide the X and Y data into bins. Through a loop, we process each of the bins and assign the corresponding mean value of Z to the X and Y data. We then make a "Zgrid()", which would help us in plotting the required colour map.
You can find the documentation for each of the mentioned functions below:
Hope this helps!

类别

Help CenterFile Exchange 中查找有关 Histograms 的更多信息

标签

产品


版本

R14SP2

Community Treasure Hunt

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

Start Hunting!

Translated by