多邊形重心計算
三角形重心
- 頂點為a，b，c的三角形重心為x = (xa + xb + xc) / 3，y = (ya + yb + yc) / 3
多邊形重心
- x = (x1w1 + x2w2 + … + xnwn)/w
- y = (y1w1 + y2w2 + … + ynwn)/w
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import org.locationtech.jts.geom.coordinate;import org.locationtech.jts.geom.polygon;import org.locationtech.jts.io.parseexception;import java.util.*;import java.util.stream.collectors;/** * <p>title : polygonnodetriangle </p> * <p>description : 多邊形自身節點組成三角形</p> * @author huifer * @date 2018/10/15 */public class polygonnodetriangle { private int num = 3; private set result_p = new hashset(); public static void main(string[] args) { //0 double[] point1 = new double[]{0, 0}; //1 double[] point2 = new double[]{10, 0}; //2 double[] point3 = new double[]{20, 0}; //3 double[] point4 = new double[]{10, 10}; list<double[]> allpoint = new arraylist(); allpoint.add(point1); allpoint.add(point3); allpoint.add(point4); polygonnodetriangle polygoncenterpoint = new polygonnodetriangle(); // 外圍 polygon waiwei = polygoncenterpoint.waiwei(point1, point3, point4); // 節點三角形 list<polygon> sanjiaoxing = polygoncenterpoint.trianglemothed(allpoint); // 外圍內所有三角形 list<polygon> rangetriangle = polygoncenterpoint.getrangetriangle(waiwei, sanjiaoxing); // 重心xy double[] gravitycenterxy = polygoncenterpoint.getgravitycenterxy(rangetriangle); system.out.println(rangetriangle.size()); system.out.println("================================================"); double[] doubles = polygoncenterpoint. polygongravitypoint("polygon((0 0, 20 0, 10 10, 0 0))"); } /*** * polygon wkt 計算重心 * @param wkt * @return */ private double[] polygongravitypoint(string wkt) { if (!wkt.startswith("polygon")) { return null; } operation operation = new operation(); // 外圍數據轉 list<double[]> polygon waiwei = null; try { waiwei = operation.createpolygonbywkt(wkt); } catch (parseexception e) { e.printstacktrace(); } coordinate[] coordinates = waiwei.getcoordinates(); list<double[]> allp = new arraylist<>(); arrays.stream(coordinates).foreach( s -> { double nowx = s.x; double nowy = s.y; allp.add(new double[]{nowx, nowy}); } ); list<polygon> polygons = trianglemothed(allp); list<polygon> rangetriangle1 = getrangetriangle(waiwei, polygons); double area = waiwei.getarea(); double[] gravitycenterxy1 = getgravitycenterxy(rangetriangle1); return gravitycenterxy1; } /*** * 重心值 * @param rangetriangle * @return [x, y] */ private double[] getgravitycenterxy(list<polygon> rangetriangle) { double xarea = 0.0; double yarea = 0.0; double aarea = 0.0; for (polygon triangle : rangetriangle) { coordinate[] coordinates = triangle.getcoordinates(); double area = triangle.getarea(); double[] onegr = trianglecenterofgravity(coordinates[0], coordinates[1], coordinates[2]); xarea += onegr[0] * area; yarea += onegr[1] * area; aarea += area; } system.out.println("重心x " + xarea / aarea); system.out.println("重心y " + yarea / aarea); return new double[]{xarea / aarea, yarea / aarea}; } /*** * 范圍內三角形 * @param waiwei * @param sanjiaoxing * @return */ private list<polygon> getrangetriangle(polygon waiwei, list<polygon> sanjiaoxing) { list<polygon> triangle = new arraylist<>(); // 判斷三角形是否在面內 for (int i = 0; i < sanjiaoxing.size(); i++) { polygon polygon = sanjiaoxing.get(i); boolean within = polygon.within(waiwei); if (within) { triangle.add(polygon); } } return triangle; } /*** * 三角形重心計算 * @param a * @param b * @param c * @return */ private double[] trianglecenterofgravity(coordinate a, coordinate b, coordinate c) { double gravityx = (a.x + b.x + c.x) / 3; double gravityy = (a.y + b.y + c.y) / 3; double[] result = new double[]{gravityx, gravityy}; return result; } /*** * 測試用外包圖形 * @return */ private polygon waiwei(double[] point1, double[] point3, double[] point4) { list<double[]> ceshimian = new arraylist(); ceshimian.add(point1);// ceshimian.add(point2);// ceshimian.add(point7); ceshimian.add(point4);// ceshimian.add(point6);// ceshimian.add(point5); ceshimian.add(point3); string polygonforlist = createpolygonforlist(ceshimian); operation op = new operation(); polygon polygonbywkt = null; try { polygonbywkt = op.createpolygonbywkt(polygonforlist); return polygonbywkt; } catch (parseexception e) { e.printstacktrace(); } return null; } /*** * 生成所有三角形 * @param allpoint * @return */ private list<polygon> trianglemothed(list<double[]> allpoint) { // 索引 -> 點坐標 map<string, double[]> indexofpoint = new hashmap(); for (int i = 0; i < allpoint.size(); i++) { indexofpoint.put(string.valueof(i), allpoint.get(i)); } // 排序結果 sort((list) indexofpoint.keyset().stream().collect(collectors.tolist()), new hashset()); // 刪除元素相同后的集合 // 所有三角形 list<polygon> alltriangle = new arraylist(); for (object onedataobj : result_p) { //這一行數據 set onedatalist = (set) onedataobj; // 這一行數據的三角形數據 list<double[]> trianglepoint = new arraylist(); onedatalist.foreach( s -> trianglepoint.add(indexofpoint.get(s) )); polygon triangle = createtriangle(trianglepoint); if (triangle != null) { alltriangle.add(triangle); } } // 所有三角形結束 return alltriangle; } /*** * 從點坐標集合中創建一個面 * @param points * @return */ private static string createpolygonforlist(list<double[]> points) { string end = "))"; string res = "polygon(("; operation op = new operation(); for (double[] point : points) { string x = double.tostring(point[0]); string y = double.tostring(point[1]); res += x + " " + y + ", "; } res += double.tostring(points.get(0)[0]) + " " + double.tostring(points.get(0)[1]); res += end; try { op.createpolygonbywkt(res); } catch (parseexception e) { e.printstacktrace(); } return res; } /*** * 創建三角形 * @param trianglepoint * @return polygon */ private static polygon createtriangle(list<double[]> trianglepoint) { operation op = new operation(); string trianglewkt; boolean istri = istriangle(trianglepoint); if (istri) { trianglewkt = "polygon((" + trianglepoint.get(0)[0] + " " + trianglepoint.get(0)[1] + ", " + trianglepoint.get(1)[0] + " " + trianglepoint.get(1)[1] + ", " + trianglepoint.get(2)[0] + " " + trianglepoint.get(2)[1] + ", " + trianglepoint.get(0)[0] + " " + trianglepoint.get(0)[1] + "))"; try { polygon polygonbywkt = op.createpolygonbywkt(trianglewkt); return polygonbywkt;// return trianglewkt; } catch (parseexception e) { e.printstacktrace(); } } return null; } /*** * 判斷三角形 * @param trianglepoint * @return */ private static boolean istriangle(list<double[]> trianglepoint) { double[] doubles = trianglepoint.get(0); double[] doubles1 = trianglepoint.get(1); double[] doubles2 = trianglepoint.get(2); double len = math.sqrt(math.pow(doubles[0] - doubles1[0], 2) + math.pow(doubles[1] - doubles1[1], 2)); double len1 = math.sqrt(math.pow(doubles[0] - doubles2[0], 2) + math.pow(doubles[1] - doubles2[1], 2)); double len2 = math.sqrt(math.pow(doubles1[0] - doubles2[0], 2) + math.pow(doubles1[1] - doubles2[1], 2)); if ((len + len1 > len2) && (len + len2 > len1) && (len1 + len2 > len)) { return true; } return false; } /*** * 不重復排列 (元素不相同) * @param datas * @param target */ private void sort(list datas, set target) { if (target.size() == this.num) { this.result_p.add(target); return; } for (int i = 0; i < datas.size(); i++) { list newdatas = new arraylist(datas); set newtarget = new hashset(target); newtarget.add(newdatas.get(i)); newdatas.remove(i); sort(newdatas, newtarget); } }} |
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原文鏈接：https://blog.csdn.net/staHuri/article/details/83058930
