Extracting closed contours of streamfunction

I have 2D streamfunction(x,y). I would like to know how can I extract closed contour of streamfunction only without providing threshold. And obtain the rough radius of the circle with centre

Thanking you

Answer 1

[KSSV]

Did you try this? https://in.mathworks.com/help/matlab/ref/streamline.html

[CODER]

Yes, but this is a way to plot streamlines , however, not extraction of closed contour.

[KSSV]

Plot the function and use contour. Read about contour.

[CODER]

OK, that's doable but any idea/crtiteria to be used for extracting the closed contour boundary without threshold ?!.

Thanking you

[KSSV]

Get the points of the contour and try this: https://in.mathworks.com/matlabcentral/answers/583547-set-of-points-form-a-polygon

Or share your data and what have you tried.

[CODER]

[KSSV]

You have any specific line/ region to extract?

[CODER]

Yes I would like to extract only those circular streamfunction contour which are indicated. Basically it will be having three circular contours only and the contours which are not circular should be removed.Applying theshold would produce contour that are not circular so I avoid threshold.