Extracting points from a plot that do not appear in the original data

I was wondering if it is possible to extract information from a plot that only 'exists' in the plot itself, not the underlying data. For example, in the attached image I would like to extract the data point where the two lines intersect - however this does not exist in the original data - the closet 'real' points plotted in yellow.

I know I could take a ginput and have the user manually click on the intersection point, but was wondering if it is possible to automate this?

Best,

Joe

Answer 1

[Adam Danz]

Here's a demo

% Order is important! 
% Line 1 is defined by the first two values. Line 2 is defined by second two values.
x = [5, 6, 5, 6];           % x coordinates of 4 points
y = [4.5, 6.5, 6.5, 4.5];   % y coordinates of 4 points

% Define function that calculates intersection point
getIntersect = @(x,y)[x(1)*y(2)-x(2)*y(1), x(3)*y(4)-x(4)*y(3)] / [y(2)-y(1), y(4)-y(3); -(x(2)-x(1)),-(x(4)-x(3))]; 
% xyIntersect is a [1 x 2] vector if (x,y) coordinates of intersection. 
xyIntersect = getIntersect(x,y); 

[Adam Danz]

Credit for this idea:

https://www.mathworks.com/matlabcentral/answers/341125-find-intersection-point-of-two-lines-when-i-have-their-coordinates