Get data inside a defined circle from a graph.

[babu726]

I have 3 column of data and I am plotting a surface plot where 1st and second column represents x and y coordinate of the graph and 3rd column is intensity. This works. I get a intensity plot (and also a 2d array). 

What I want to do next is draw a circle of specified size and get the data (2d array) inside that circle. If 50% or more of any of the pixels are inside the circle, I would take it to be inside the circle.

Can I get some help how to do this?

[billko]

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@babu726 wrote:

I have 3 column of data and I am plotting a surface plot where 1st and second column represents x and y coordinate of the graph and 3rd column is intensity. This works. I get a intensity plot (and also a 2d array). 

What I want to do next is draw a circle of specified size and get the data (2d array) inside that circle. If 50% or more of any of the pixels are inside the circle, I would take it to be inside the circle.

Can I get some help how to do this?

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You're probably thinking of trying to do that in a graphical way, but maybe the easiest way is to plot the circle but use math to decide whether or not each point falls within the circle.

[falkpl]

the math should be straight forward, sqrt(dx^2+dy^2)>r remove point else it is in the circle where dx and dy are the distances of the point from the center x,y.