Showing repeat data points in XY/scatter plot

I'm trying to figure out a way to show in a scatter plot a way to make points darker or larger if they appear more than once. Lets say you have 3 points, and 2 are the exact same x,y coordinates, but plotting this you would only see 2 points that look the same on the plot. How can the ones that are repeats look different? I was trying to write a function to make new arrays with repeat data, but this is proving difficult as well.

Answer 1

[Sean de Wolski]

%Data  
x = ones(1,12);
y = [1 1 2 3 3 3 4 5 6 2 2 2];

%Engine
[uxy, jnk, idx] = unique([x.',y.'],'rows');
szscale = histc(idx,unique(idx));

%Plot Scale of 25 and stars
scatter(uxy(:,1),uxy(:,2),'p','sizedata',szscale*25)

[Walter Roberson]

This is fine for integer coordinates; if the coordinates have fractions, then the fuller accumarray() solution I linked to would be necessary.

Answer 2

[Walter Roberson]

Please see my answer to this. Be sure to expand the comments as the details show up there.