Finding the nearest XY coordinates

I've got a point in 2d image for example the red Dot in 开发者_如何学Pythonthe given picture and a set of n points blue dot (x1,y1)...(xn,yn) and I want to find nearest point to (x0,y0) in a way better than trying all points. Like to have best possible solution. Would appreciate if you share any similar class if you have.

There are many approaches to this, the most common probably being using some form of space partitioning to speed up the search so that it is not O(n). For details, see Nearest neighbor search on Wikipedia.

Most solutions that we could suggest would depend on a little bit more knowledge, I am going to go out on a limb and say that unless you already know that you are short on time. I.e. there are tens of thousands of blue dots or you have to do thousands of these calculations in a short time. "Linear Search" will serve you well enough.

Don't bother calculating the actual distance, save yourself calculating the square root and use this as the "distance".

Most other methods use more complex data structures to sort the points in respect to their geometric arrangement. But are a lot harder to implement.