area_center_points_xldarea_center_points_xldAreaCenterPointsXldAreaCenterPointsXldarea_center_points_xld (算子名称)

名称

area_center_points_xldarea_center_points_xldAreaCenterPointsXldAreaCenterPointsXldarea_center_points_xld — Area and center of gravity (centroid) of contours and polygons treated as point clouds.

参数签名

描述

area_center_points_xldarea_center_points_xldAreaCenterPointsXldAreaCenterPointsXldAreaCenterPointsXldarea_center_points_xld calculates the area and center of gravity (centroid) of the point clouds given by contours or polygons XLDXLDXLDXLDXLDxld (i.e., the order of the points in the contour or polygon is not taken into account). The area corresponds to the number of points in the point cloud. The centroid is given by the arithmetic mean of all points. If the contour or polygon is closed (end point = start point), the end point of the contour or polygon is not taken into account to avoid that it receives twice the weight of the other points.

area_center_points_xldarea_center_points_xldAreaCenterPointsXldAreaCenterPointsXldAreaCenterPointsXldarea_center_points_xld should be used if the contour XLDXLDXLDXLDXLDxld intersects itself or if it is not possible to close the contour using a line from end to start point without self-intersection, because in this case area_center_xldarea_center_xldAreaCenterXldAreaCenterXldAreaCenterXldarea_center_xld does not produce useful results. To test whether the contours or polygons intersect themselves, test_self_intersection_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXldTestSelfIntersectionXldtest_self_intersection_xld can be used.

If more than one contour or polygon is passed, the results are stored in tuples in the same order as the respective contours or polygons in XLDXLDXLDXLDXLDxld.

注意

Even if the contour or polygon XLDXLDXLDXLDXLDxld is not intersecting itself, the result of area_center_points_xldarea_center_points_xldAreaCenterPointsXldAreaCenterPointsXldAreaCenterPointsXldarea_center_points_xld significantly differs from the result of area_center_xldarea_center_xldAreaCenterXldAreaCenterXldAreaCenterXldarea_center_xld as it is calculated from the point cloud and not from the enclosed region.

运行信息

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Automatically parallelized on tuple level.

参数表

Complexity

Let n be the number of points of the contour or polygon. Then the run time is O(n).

结果

area_center_points_xldarea_center_points_xldAreaCenterPointsXldAreaCenterPointsXldAreaCenterPointsXldarea_center_points_xld returns 2 ( H_MSG_TRUE) if the input is not empty. If the input is empty the behavior can be set via set_system(::'no_object_result',<Result>:)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>). If necessary, an exception is raised.

可能的前置算子

gen_contours_skeleton_xldgen_contours_skeleton_xldGenContoursSkeletonXldGenContoursSkeletonXldGenContoursSkeletonXldgen_contours_skeleton_xld, smooth_contours_xldsmooth_contours_xldSmoothContoursXldSmoothContoursXldSmoothContoursXldsmooth_contours_xld, gen_polygons_xldgen_polygons_xldGenPolygonsXldGenPolygonsXldGenPolygonsXldgen_polygons_xld

可替代算子

area_center_xldarea_center_xldAreaCenterXldAreaCenterXldAreaCenterXldarea_center_xld

参考其它

moments_points_xldmoments_points_xldMomentsPointsXldMomentsPointsXldMomentsPointsXldmoments_points_xld, moments_any_points_xldmoments_any_points_xldMomentsAnyPointsXldMomentsAnyPointsXldMomentsAnyPointsXldmoments_any_points_xld, area_centerarea_centerAreaCenterAreaCenterAreaCenterarea_center, moments_region_2ndmoments_region_2ndMomentsRegion2ndMomentsRegion2ndMomentsRegion2ndmoments_region_2nd

模块

Foundation

---