How are the points in a level curve chosen in pyplot?
The function is evaluated at every grid node, and compared to the iso-level. When there is a change of sign along a cell edge, a point is computed by linear interpolation between the two nodes. Points are joined in pairs by line segments. This is an acceptable approximation when the grid is dense enough.
I want to know how the contours levels are chosen in pyplot.contour. What I mean by this is, given a function f(x, y), the level curves are usually chosen by evaluating the points where f(x, y) = c, c=0,1,2,... etc. However if f(x, y) is an array A of nxn points, how do the level points get chosen? I don't mean how do the points get connected, just simply the points that correspond to A = c