Removing Points Along a Diagonal Line

1 次查看（过去 30 天）

racqs 2019-7-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474119-removing-points-along-a-diagonal-line

评论： darova 2019-7-31

I have a slope that i have discretized into points. However along the diagonal line I would like to remove all the points to the right of this line. Is this possible? All I have been able to do is remove the points as shown in the second figure but my slope actually looks like the first figure. The points to be reomved are all those lying within the shaded region. Is this possible?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

infinity 2019-7-30

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474119-removing-points-along-a-diagonal-line#answer_385471

Hello,

I would suggest you a solution,

Since you have known two points of slope, which are (40,35) and (74.4, 15), you can easily get a segment passing to these points. Let say, y = ax + b.

Then, you can define a function, for example phi(x,y) = ax + b - y. As it can seen that phi(x,y) > 0 if (x,y) is in the left of the slope and phi(x,y) < 0 if (x,y) is in the right of the slope and phi(x,y) = 0 if (x,y) is in the slope. This technique is called "levelset method".

Now, what you can do is to use the phi funtion to check a point is in the left or the right of the slope. If it is in the right, you just eleminate it.

5 个评论
显示 3更早的评论隐藏 3更早的评论

infinity 2019-7-31

编辑：infinity 2019-7-31

在 MATLAB Online 中打开

Hello,

So, you could use for loop (or even don't need for loop) to check wheather a nodes in A is in B or not. If it is not, you store it into a new variable. For example,

clear
A = [1 2; 3 4; 5 6];
B = [3 4; 5 6];
C = [];
for i = 1:size(A,1)
    if ~ismember(A(i,1),B(:,1)) || ~ismember(A(i,2),B(:,2))
    C = [C; A(i,:)];
    end
end