Displaying random numbers as a graph

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Mustafa Vural 2020-10-17

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https://ww2.mathworks.cn/matlabcentral/answers/617248-displaying-random-numbers-as-a-graph

评论： Star Strider 2020-10-18

I am generating random numbers with the rejection sampling, like in this picture. How can I see my generated random numbers as points, like in this picture?

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Adam Danz 2020-10-18

plot()

scatter()

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Star Strider 2020-10-18

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在 MATLAB Online 中打开

One approach is to use the inpolygon function:

x = linspace(0, 10);
y = exp(-(x-5).^2)*0.2;
r = rand(1000,2).*[10 0.25];
[in,on] = inpolygon(r(:,1),r(:,2), x, y);
figure
plot(x,y)
hold on
plot(r(:,1), r(:,2),'.r')
plot(r(in,1), r(in,2), '.g')
hold off

producing:

Experiment with it to get the result you want.

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Star Strider 2020-10-18

在 MATLAB Online 中打开

It appears that the function plots correctly, the only problem being the random dots. (I was going on the data in the plot image you posted.)

This is the reason it is extremely important to post the exact problem you want help with. The example image helps significantly. I will go by it to define my code in the absence of other information.

You will need to adjust the vector elements that multiply the rand matrix. This is defined as:

r = rand(1000,2).*[x_limit y_limit];

so here:

r = rand(1000,2).*[2 1.2];

to create the dots defining their x-values from 0 to 2 and y-values from 0 to 1.2.

Again using my function because I still do not have your parameters:

x = linspace(0, 2);
y = exp(-(x-1).^2*20)*1.15;
r = rand(1000,2).*[2 1.2];
[in,on] = inpolygon(r(:,1),r(:,2), x, y);
figure
plot(x,y)
hold on
plot(r(:,1), r(:,2),'.r')
plot(r(in,1), r(in,2), '.g')
hold off