intersection

This question already has an answer here: Test if lists share any items in python 9 answers Suppose I have two lists, L and M. Now I want to know if they share an element. Which would be the fastest way of asking (in python) if they share an element? I don't care which elements they share, or how many, just if they share or not. For example, in this case L = [1,2,3,4,5,6] M = [8,9,10] I should get False, and here: L = [1,2,3,4,5,6] M = [5,6,7] I should get True. I hope the question's clear. Thanks! Manuel Or more concisely if set(L) & set(M): # there is an intersection else: # no intersection

I'm stuck with this little problem and my algorithm to solve this doesn't hold for all cases. Does anybody has an idea how to solve this? Here's an example polygon: example http://img148.imageshack.us/img148/8804/poly.png Formal description We have a list of points in CW order defining the polygon. We also can query whether a point is a cutting point with is_cut(p) , where p is a given point. Now we want to compute new polygons caused by this "cut". The algorithm should do this: Input: {a, c1, b, c4, c, c5, d, c6, e, c3, f, c2} Output: {a, c1, c2} , {b, c4, c3, f, c2, c1} , {d, c6, c5} , {e,

I'm trying to find a way to calculate the intersection between a b-spline and a straight line. So far Google hasn't been much help. The most efficient algorithm that I've heard of is called Bezier clipping. Here's a book chapter on curve and spline intersection (pdf). A pure mathematical approach: Transform the spline and the line so that the line lies on the X axis. Calculate the points on the spline where Y = 0 (depends on the order of the spline). Transform these points back to your original cordinate system. If this is the way you are going I can work out the necessary formulas. Your best

I have two rays on a 2D plane that extend to infinity, but both have a starting point. They are both described by a starting point and a vector in the direction of the ray extending to infinity. I want to find out if the two rays intersect, but I don't need to know where they intersect (it's part of a collision detection algorithm). Everything I have looked at so far describes finding the intersection point of two lines or line segments. Is there a fast algorithm to solve this? Given: two rays a, b with starting points (origin vectors) as, bs, and direction vectors ad, bd. The two lines

My aim is to find out values of intersection of arrays a and b and store them into a new array c so the printout will be : 3,10,4,8. How do I assign given values to a 3rd array c ? public static void main(String[] args) { int a[] = {3, 10, 4, 2, 8}; int[] b = {10, 4, 12, 3, 23, 1, 8}; int[] c; int i=0; for(int f=0;f<a.length;f++){ for(int k=0;k<b.length;k++){ if(a[f]==b[k]){ //here should be a line that stores equal values of 2 arrays(a,b) into array c } } } for (int x=0; x<c.length; x++){ System.out.println(c[i]); } } } sakthisundar This should be an easy way to do. int a[] = {3, 10, 4, 2, 8}

First of all, my purpose is to randomly get only one element in both known sets. So my original method is firstly intersect two sets. And then randomly pick up a element from the intersected set. But this is foolish, because that I only need a elements but a intersected set. So I need to find the algorithm of set.intersection(). I compare the cost time between the methods of 'set.intersection()' and 'for{for{}}'. Set.intersection() is more faster than other one(100 times). So using 'for{for{}}' to pick up a randomly elements is not a wise idea. What's the algorithm behind set.intersection() in

This question is an exact duplicate of: Swift: detecting intersection from sprite kit SKShapeNode drawings 1 answer Is there an easy way to draw shapes in Swift (preferrably with Sprite-Kit) and then detect if and where they intersect? Like here's an intersecting shape: Rob If this consists of a series of line segments, one can adapt Martin R's answer to UIBezierPath intersect to not only detect intersections, but to also identify where the intersections are: func intersectionBetweenSegments(p0: CGPoint, _ p1: CGPoint, _ p2: CGPoint, _ p3: CGPoint) -> CGPoint? { var denominator = (p3.y - p2.y)