How do I measure density of random point with a fixed area in MATLAB?
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There had a 9x9 area and I have generate a lot of point with this area in random.
How do I measure density of the red point (e.g. Bottom left).
Somebody can give something sample code to let me study with this topic? It is very helpful to my project research.
3 Comments
Mathieu NOE
on 21 Jan 2021
hello
these are plot format option * = star, g = green, o = circle , r = red
Accepted Answer
Adam Danz
on 20 Jan 2021
Edited: Adam Danz
on 20 Jan 2021
Use histogram2() or histcounts2() to compute 2D density.
Demo:
xy = randi(400,50,2);
subplot(1,2,1)
plot(xy(:,1), xy(:,2), 'r.')
axis equal
grid on
xlim([1,400])
ylim([1,400])
title('raw data')
binEdges = linspace(1,400,4);
set(gca,'XTick',binEdges, 'YTick',binEdges)
% Compute density in 3X3 bins
subplot(1,2,2)
h = histogram2(xy(:,1), xy(:,2), binEdges,binEdges,...
'DisplayStyle','tile','ShowEmptyBins','on');
axis equal
grid on
xlim([1,400])
ylim([1,400])
title('Density')
set(gca,'XTick',0:100:400, 'YTick',0:100:400)
cb = colorbar();
ylabel(cb,'Density')
% To label counts
[xTxt, yTxt] = ndgrid(h.XBinEdges(2:end)-h.BinWidth(1)/2, ...
h.YBinEdges(2:end)-h.BinWidth(2)/2);
labels = compose('%.0f', h.Values);
hold on
text(xTxt(:), yTxt(:), labels(:), 'VerticalAlignment', 'Middle', 'HorizontalAlignment','Center')
12 Comments
ytu1990
on 21 Dec 2021
After calculating the density, how to return the density value to be linked to the coordinate of original point?
For example, return the value "9" to the points in the (1,1) grid...
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