MATLAB: Scatter ‘o’ Marker circularity

scatter marker shape

Hi, I am trying to use scatter function in Matlab with circle makers. But I noticed that the marker 'o' is not fully circle. it is more of an oval ( wider in y direction). Is there anyway to make it a perfect circle?

Best Answer

The 'o' marker is implemented as an octagon (at least up to R2014a). On my R2014a OS-X system, they appear to retain their aspect ratio no matter how large I make them and no matter what aspect ratio I have in effect or how wide I make the axes (that is, they are drawn "after" the other items are sized.)

If you have R2012a or later and Image Processing Tookbox, then you could try viscircles() -- but note that any circles drawn that way are going to be subject to aspect ratio considerations; see "axis equal" or set the "dataaspect" property of the axes.

Related Solutions

MATLAB: What’s the diameter of the standard circle marker ‘o’ in scatter3 plot

The size of scatter objects are in point units where 1 point equals 1/72 inch.

Plot a single point and look at it's SizeData.

h = scatter3(0,0,0); 
h.SizeData
% ans =
%     36

so, the default size is 36/72 or 1/2 inch.

MATLAB: How to make round ‘o’ markers render as round when saving to png

That looks like an issue that the OpenGL driver has on some graphics cards when drawing wide lines. If so, you have a couple of options. Here are a few:

The simplest is to disable the edges and just use the fill color of the markers:

plot(randn(1,120),'o','MarkerFaceColor','black','MarkerEdgeColor','none')

Another option would be to tell export_fig to use the painters renderer.
Starting MATLAB with -softwareopengl might help, but I think that the Microsoft OpenGL implementation in Windows 7 is one of the ones that has this issue. Perhaps you're already getting that one. What does "opengl info" report?

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Related Solutions

MATLAB: What’s the diameter of the standard circle marker ‘o’ in scatter3 plot

MATLAB: How to make round ‘o’ markers render as round when saving to png

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