I want to plot a scatter plot with filled markers and make them semi-transparent so when two or more markers overlap, the overlapping area will be more opaque.
I naively thought
sg = scatter(rand(1000,1),rand(1000,1), 'filled');
alpha(0.5)
would work, but it doesn't. Also
set(get(sg, 'Children'), 'FaceAlpha', 0.2)
doesn't work. Any ideas?
Here's some sample matlab code that makes transparent scatterplot points with patch objects:
x=randn(5000,1)*20;
y= randn(5000,1)*20;
t= 0:pi/10:2*pi;
figure();
for i=1:size(x)
pb=patch((sin(t)+ x(i)),(cos(t)+y(i)),'b','edgecolor','none');
alpha(pb,.1);
end