How do I generate multiple sets of arrays automatically?

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Kavanapi 2016-1-31

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https://ww2.mathworks.cn/matlabcentral/answers/265949-how-do-i-generate-multiple-sets-of-arrays-automatically

评论： Stephen23 2016-1-31

The code currently generates a random scatter of 30 points. An array of x and y values are saved separately in x1 and y1.

I want to make multiple sets of x and y coordinates, so I can have multiple different arrays. For example if I wanted three different random scatters, the code would generate the arrays x1, y1, x2, y2, x3, y3, or if I wanted ten, then there would be ten x y pairings. And each pairing would generate a random scatter of points.

If anyone would be able to advise me, that would be great! I tried making a second for loop, but I couldn't figure out how to make it work... Here's the code I have written so far:

n = 30; %number of elements
R = 0.3; %maximum radius
x1 = zeros(n,1);
y1 = zeros(n,1);
for i = 1:1:n
     x1(i) = unifrnd(-R,R);
     y1(i) = unifrnd(-R,R);
end
figure(1)
plot(x1,y1, '.')
%save('optArray','x1','y1')

Thanks in advance for your help!

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Stephen23 2016-1-31

编辑：Stephen23 2016-1-31

Don't do this! Dynamically named variables are a slow, buggy, amateur, and obfuscated way to program. Using them means removing lots of inbuilt tools that help you to write code properly (code hinting, mlint messages, etc). There are so many reasons why that creating variable names dynamically is such a bad idea (no matter how much beginners love them):

http://www.mathworks.com/matlabcentral/answers/196952-how-to-create-new-variables-in-batches-with-strcat

http://www.mathworks.com/matlabcentral/answers/57445-faq-how-can-i-create-variables-a1-a2-a10-in-a-loop

http://www.mathworks.com/matlabcentral/answers/143-how-do-i-make-a-series-of-variables-a1-a2-a3-a10

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Answer 1

Stephen23 2016-1-31

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/265949-how-do-i-generate-multiple-sets-of-arrays-automatically#answer_208006

编辑：Stephen23 2016-1-31

在 MATLAB Online 中打开

Here is your code, with a small change to store the data values in matrices:

M = 10;  % number of repetitions
N = 30;  % number of elements
R = 0.3; % maximum radius
X = zeros(N,M); % changed to matrix
Y = zeros(N,M); % changed to matrix
C =  cell(1,M);
for m = 1:M
    for n = 1:N
        X(n,m) = unifrnd(-R,R);
        Y(n,m) = unifrnd(-R,R);
    end
    C{m} = sprintf('test %d',m);
end
figure(1)
plot(X,Y, '.')
legend(C,'Location','BestOutside')
%save('optArray','X','Y','C')

I also plotted them all in one figure, and included a legend. Note how easy this was to do!

Do NOT use Dynamically Named Variables

Using dynamically named variables would make all of this much more complicated, slower, and buggier. In fact you should NOT create variable names dynamically (such as X1, X2, X3, etc), because although beginners all seem to believe that this is a great idea it really is not. Creating dynamic variable names is slow, buggy, and hard to read. Here is an explanation of why creating variable names dynamically is such a bad way to write code:

http://www.mathworks.com/matlabcentral/answers/196952-how-to-create-new-variables-in-batches-with-strcat

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Kavanapi 2016-1-31

Thank you Stephen. The dynamic variable way is the most obvious method for us beginners I think, but I see now why it's no use... The code you've provided does the job well!

Stephen23 2016-1-31

My Pleasure! We were all beginners once, there is nothing wrong with that! If you take the time to read those links you will learn some useful information.

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