[英]How to plot points outside certain polygon area in MATLAB
我一直在寻找一种在多边形区域之外绘制点的方法(在我的情况下为六边形)。 这是我要实现的方案,我有一个位于大六角形内的小六角形。 图片如下:
在图片中,我创建了一个小六边形(其区域以浅红色表示),并使用inpolygon
在其中生成了一个随机点(在我的情况下为三个)。 当我要绘制大六边形(浅紫色表示)中的点(红色三角形) 而不触碰小六边形区域时,会出现问题 。 对于这种简单的解决方案,我在网上四处寻找,但没有结果,为期3天。
我会很感激我能得到的任何帮助或指导 。 非常感谢!
我的代码如下:
clear
clc
bighexagon = 20;
smallhexagon = 4;
axis_min = 0;
axis_max = 40;
axis([axis_min axis_max axis_min axis_max],'square');
hold on
L = linspace(30,390,7);
bhex_x = bighexagon * (1+cosd(L))';
bhex_y = bighexagon*(1+sind(L))';
L2 = linspace(30,390,7);
shex_x = smallhexagon * (1+cosd(L2))';
shex_y = smallhexagon * (1+sind(L2))';
plot(bhex_x,bhex_y,'LineWidth',3);
%---Move small hexagon into big hexagon
shex_vertices_x2(:,1) = shex_x + 16;
shex_vertices_y2(:,1) = shex_y + 16;
plot(shex_vertices_x2(:,1),shex_vertices_y2(:,1),'--k','LineWidth',3);
%---Plot points in small hexagon
no = 3;
point_x2 = (smallhexagon+20) - rand(1,9*no)*2*smallhexagon;
point_y2 = (smallhexagon+20) - rand(1,9*no)*2*smallhexagon;
inside = inpolygon(point_x2,point_y2,shex_vertices_x2,shex_vertices_y2);
point_x2 = point_x2(inside);
point_y2 = point_y2(inside);
idx2 = randperm(length(point_x2));
point_x2 = point_x2(idx2(1:no));
point_y2 = point_y2(idx2(1:no));
plot(point_x2,point_y2,'ro','MarkerSize',1.5,'LineWidth',1, ...
'MarkerFaceColor','r');
%---Plot points in big hexagon
no2 = 4;
point_x = (bighexagon+20) - rand(1,9*no2)*2*bighexagon;
point_y = (bighexagon+20) - rand(1,9*no2)*2*bighexagon;
inside2 = inpolygon(point_x,point_y,bhex_x,bhex_y);
point_x = point_x(inside2);
point_y = point_y(inside2);
idx = randperm(length(point_x));
point_x = point_x(idx(1:no2));
point_y = point_y(idx(1:no2));
plot(point_x,point_y,'g^','MarkerSize',3,'LineWidth',3, ...
'MarkerFaceColor','g');
UPDATE
感谢Hoki
的建议,我终于能够解决这个问题。
请注意,我在代码中更改了此部分:
validpoint = inpolygon(point_x,point_y,bhex_x,bhex_y) & ~inpolygon(point_x,point_y,shex_vertices_x2,shex_vertices_y2);
希望这可以消除混乱,也可以帮助其他用户。 我要感谢Hoki
和xenoclast
的帮助。
代码如下:
clear
clc
bighexagon = 20;
smallhexagon = 4;
axis_min = 0;
axis_max = 40;
axis([axis_min axis_max axis_min axis_max],'square');
hold on
L = linspace(30,390,7);
bhex_x = bighexagon * (1+cosd(L))';
bhex_y = bighexagon*(1+sind(L))';
L2 = linspace(30,390,7);
shex_x = smallhexagon * (1+cosd(L2))';
shex_y = smallhexagon * (1+sind(L2))';
plot(bhex_x,bhex_y,'LineWidth',3);
%---Move small hexagon into big hexagon
shex_vertices_x2(:,1) = shex_x + 16;
shex_vertices_y2(:,1) = shex_y + 16;
plot(shex_vertices_x2(:,1),shex_vertices_y2(:,1),'--k','LineWidth',3);
%---Plot points in small hexagon
no = 3;
point_x2 = (smallhexagon+20) - rand(1,9*no)*2*smallhexagon;
point_y2 = (smallhexagon+20) - rand(1,9*no)*2*smallhexagon;
inside = inpolygon(point_x2,point_y2,shex_vertices_x2,shex_vertices_y2);
point_x2 = point_x2(inside);
point_y2 = point_y2(inside);
idx2 = randperm(length(point_x2));
point_x2 = point_x2(idx2(1:no));
point_y2 = point_y2(idx2(1:no));
plot(point_x2,point_y2,'ro','MarkerSize',1.5,'LineWidth',1, ...
'MarkerFaceColor','r');
%---Plot points in big hexagon
no2 = 30;
point_x = (bighexagon+20) - rand(1,9*no2)*2*bighexagon;
point_y = (bighexagon+20) - rand(1,9*no2)*2*bighexagon;
%---As per Hoki's suggestion, it ensure the points are outside the small hexagon
validpoint = inpolygon(point_x,point_y,bhex_x,bhex_y) & ...
~inpolygon(point_x,point_y,shex_vertices_x2,shex_vertices_y2);
point_x = point_x(validpoint);
point_y = point_y(validpoint);
idx = randperm(length(point_x));
point_x = point_x(idx(1:no2));
point_y = point_y(idx(1:no2));
plot(point_x,point_y,'g^','MarkerSize',3,'LineWidth',3, ...
'MarkerFaceColor','g');
如果内部六边形是由顶点定义的,则可以使用inpolygon
( link )测试给定点是否在其中。
请在inside2 = inpolygon(point_x,point_y,bhex_x,bhex_y);
之后添加以下两行进行检查inside2 = inpolygon(point_x,point_y,bhex_x,bhex_y);
in1 = inpolygon(point_x,point_y,shex_vertices_x2,shex_vertices_y2);
inside2= logical(inside2-in1);
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