Question

考虑两个维度(x,y)。

我想在Matlab中构建点{@ 1}}和-0.8<x<0.1的点网格。从这样的网格我想删除所有点0.1<y<0.9和-0.7<=x<=0。

我使用＆＃34;网格精度＆＃34;等于0.2<=y<=0.8。

这里我的代码似乎没有做我想要的

0.001

%outside square xgrid=(-0.8+0.001:0.001:0.1-0.001); ygrid=(0.1+0.001:0.001:0.9-0.001); [p,q] = meshgrid(xgrid, ygrid); grid = [p(:) q(:)]; %inside square xgrid1=(-0.7:0.001:0); xgrid1=(0.2:0.001:0.8); [p,q] = meshgrid(xgrid1, ygrid1); grid1 = [p(:) q(:)]; %delete inside square from outside square grid(ismember(grid,grid1, 'rows'),:)=[];似乎无法识别Ismember中的所有点都在grid1中。我做错了什么？

Answer 1

请参阅此代码，其中包含描述要执行操作的注释

% Define grid precision, h, for more clarity and easier editing
h = 1e-3;
% Specify xgrid and ygrid using 2 parts each
xgrid = [-0.8+h:h:-0.7-h, 0+h:h:0.1];
ygrid = [0.1+h:h:0.2-h, 0.8+h:h:0.9-h];
% Make grid and use it to get coordinate pairs
[p,q] = meshgrid(xgrid, ygrid);
grid = [p(:) q(:)];

您正在尝试创建一个大网格，然后从中删除一个内部方块。上面的代码只创建了生成的矩阵，从不首先创建内部正方形。

修改

OP澄清了只应删除-0.7<=x<=0.0和0.2<=y<=0.8的坐标，以上是针对“OR”的情况。以下是所谓的“AND”案例......

% Define grid precision, h, for more clarity and easier editing h = 1e-3; % Specify xgrid and ygrid using 2 parts each xgrid = [-0.8+h:h:0.1]; ygrid = [0.1+h:h:0.9-h]; % Make grid and use it to get coordinate pairs [xx, yy] = meshgrid(xgrid, ygrid); % Turn grids into column vectors xx = xx(:); yy = yy(:); % Logical indexing for where range removal condition is met idx = (xx >= -0.7 & xx <= 0.0) & (yy >= 0.2 & yy <= 0.8) % grid is all values of xx and yy which are NOT true in idx, so ~idx grid = [xx(~idx) yy(~idx)];

在Matlab中构造点网格

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