![]() I would use a cheap a DistanceQuick to dismiss it cheapĭo you really need double? That is expensive. If you want a more sophisticated algorithm for Closest, then you need to do some research on this well-studied problem: Now all you have to do is efficiently implement Closest, which you should be able to do given the previous hints about computing distances cheaply and so on. Now that we have the signature correct, the algorithm is simple: ImmutableList OrderByDistance(Point start, ImmutableSet points) Do we need the set to contain at least one point? No. The right contract is: ImmutableList OrderByDistance(Point start, ImmutableSet points) I like nothing about any of this this sounds like a ball of potential bugs. The contract is: the list must contain at least one element, the list is destroyed (!!!) by the method, the first element is special, and the result is a mutable list. Let's start by critiquing the interface: List OrderByDistance(List pointList) In particular, the accepted answer is simply wrong. Usage: var sortedPoints = PointsSorter.OrderByDistance(PointsSorter.GeneratePoints(500000),Įxecution time on my PC (in Debug): ~15 seconds. Iterate through all indexes in the 3x3 Var areaNearestPoint = GetNearestPoint(p, cells) While ((nearestPoint = null || minDist2 > minCellSize2 * (radius - 1)) & radius findAction = (i, j) => If you don't need the distance from each point to all the circles then you need a fast way to find the. This is most likely the main cause of your code being slow. The calculations are correct when you understand that it is the distance between a point and a perpetual line that continues till infinity in each direction. Comparing each point with possibly EVERY circle by calculating the distance. Then, use the Point Distance tool (Details here: ). Use the formula for the distance but just skip the square root. Int maxRadius = Math.Max(Math.Max(pi, cells.GetLength(0) - pi), Math.Max(pj, cells.GetLength(1) - pj)) ĭouble minDist2 = // To avoid access to modified closure Right click on the new table, Display XY Data, select Longitude for the X and Latitude for Y, and select the map's coordinate system to create an events layer. Int j = (int)((p.Y - minY) / (maxY - minY) * gridNy) Ĭells.AddLast(p) Int i = (int)((p.X - minX) / (maxX - minX) * gridNx) Find the entire space occupied by the pointsĭouble minCellSize2 = Pow2(Math.Min((maxX - minX) / gridNx, (maxY - minY) / gridNy)) From a geometrical point of view, the first step to measure the distance from one point to another, is to create a straight line between both points, and then measure the length of that segment. Public static List OrderByDistance(List points, int gridNx, int gridNy) The distance between a point and a continuous object is defined via perpendicularity. Next we search for the nearest point in the range I-1 GeneratePoints(int count)įor (int i = 0 i GetNearestPoint(Point toPoint, LinkedList points) Since the grid is regular, for a given point we can easily calculate its cell index (I, J). The main idea is to cover the entire space occupied by points with a rectangular regular grid.Įach grid cell contains a small subset of points which are located within the cell. Pros: Supports XY graphs Accepts JPEG, PNG, TIFF Manual tracing Linear regression of the extracted points. ![]() Besides extracting data, it offers linear regression features. Var distance = Distance(currentPoint, pointList) ĬurrentPoint = pointList Graphreader is a free online data extraction tool that supports only XY plots. PointList.RemoveAt(pointList.IndexOf(currentPoint)) įor (var i = 0 i < pointList.Count i++) Private List OrderByDistance(List pointList) private static double Distance(Point p1, Point p2) ![]() I would like some help optimizing my function to make it operate as fast as possible. The main problem with my code is: it's incredibly slow when dealing with lists that contain tons of points. it will search for the closest point to point #2. It will then add point #2 to the list of ordered by distance points.Īnd then. It will then search for the closest point to point #1. It will add point #1 to the list of ordered by distance points. The function will start with point #1 in the list. The second portion is determining the distance between the points and where all them algebra, geometry, and trigonometry skills you forgot get relearned.I wrote a function that will take a list of points and then order them so they sort of. Get Started | Geocoding API | Google Developers There is plenty of existing documentation on this here's the crux of what you need to know: The conversion of addresses to coordinates is called Geocoding, and this is where Google comes in as they have an API. There are 2 portions to this the conversion of addresses into coordinates and then calculating the distance between coordinate sets.
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