How to draw a square with specific plot points

Question

Paul 2013-10-8

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https://ww2.mathworks.cn/matlabcentral/answers/89473-how-to-draw-a-square-with-specific-plot-points

评论： Pranav 2024-7-29，23:31

I'm trying to create two squares, one larger one, and the other within it.

I attempted to create one using matrices. I create one with x = [0 0 1 1] and y = [0 1 1 0]

I wanted a line to connect each one of the points, to thus create a line. However, when I did that, I only received three lines connect between the dots for some reason. The bottom points (0,0) and (1,0) for some reason were not connected. I then attempted to make a second square, and the same thing happened, with the two lower points in regards to their Y points did not connect. I tried using the rectangle function as well, but can't get a square within a square to appear. Any help would be great. Thanks

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Answer 1

Image Analyst 2013-10-8

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https://ww2.mathworks.cn/matlabcentral/answers/89473-how-to-draw-a-square-with-specific-plot-points#answer_98921

编辑：Image Analyst 2024-7-29，2:58

在 MATLAB Online 中打开

You need 5 points - the last one is to "close off" the square, otherwise it won't be closed because you didn't draw the line back to the starting point. So, try this

% Draw first, outer rectangle.

x1=0;

x2=1;

y1=0;

y2=1;

x = [x1, x2, x2, x1, x1];

y = [y1, y1, y2, y2, y1];

plot(x, y, 'b-', 'LineWidth', 3);

hold on;

% Draw the second, inner rectangle.

x1=0.25;

x2=.75;

y1=0.25;

y2=.75;

x = [x1, x2, x2, x1, x1];

y = [y1, y1, y2, y2, y1];

plot(x, y, 'r-', 'LineWidth', 3);

% Define the plot region outer limits of the axes.

xlim([-0.5, 1.5]);

ylim([-0.5, 1.5]);

grid on;

axis equal % Make sure the aspect ratio is correct so that they look like squares.

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Paul 2013-10-8

perfect!

If you ever had to create two similar objects like this (for example two squares), would you recommend going about it another way? I tried with the rectangle function as well, it seemed potentially more convenient.

Once again, thanks for the response.

Image Analyst 2013-10-8

I think the way I did it is easier to understand than rectangle. In my mind I just visualize starting at the upper left corner and marching around the square in a clockwise fashion. First I do the x's then I do the y's. And so it's really quick for me to construct the 5 element x and y matrices.

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