Creating 'n' matrices with each one with 'n' in its name

Question

Paul Barrette 2023-9-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2022247-creating-n-matrices-with-each-one-with-n-in-its-name

编辑： Paul Barrette 2023-9-20

采纳的回答： Torsten

I am building 'n' matrices line by line:

YEAR1 = zeros(DATE_RANGE(1,3));

YEAR2 = zeros(DATE_RANGE(2,3));

YEAR3 = zeros(DATE_RANGE(3,3));

...

To avoid manually entering each line, I would like to use a looping method, e.g.,

for n=1:10

YEARn = zeros(DATE_RANGE(n,3));

end

My searches bring me to the concept of 'dynamic access' (eval), which is not recommended. But am not sure if this applies to my case.

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Stephen23 2023-9-18

编辑：Stephen23 2023-9-20

"To avoid manually entering each line, I would like to use a looping method"

That is a good approach. The best approach is to use arrays.

"My searches bring me to the concept of 'dynamic access' (eval)"

That is a very bad approach.

"But am not sure if this applies to my case."

That advice definitely applies to your case. Your approach using dynamic variable names is not recommended: your approach forces you into writing slow, complex, inefficient, obfuscated, buggy code that is hard to debug:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

So far there is no obvious reason why you could not just use basic matrices or arrays for your data, just like MATLAB is designed for. If all of those arrays are the same size then a basic 3D array would suffice.

Note that calling ZEROS with one input argument often produces unexpected results.

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Answer 1

Torsten 2023-9-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2022247-creating-n-matrices-with-each-one-with-n-in-its-name#answer_1312162

移动：Torsten 2023-9-17

在 MATLAB Online 中打开

YEAR{n} = zeros(DATE_RANGE(n,3));

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Dyuman Joshi 2023-9-17

That is, using Cell arrays to store matrices of different sizes.

https://in.mathworks.com/help/matlab/matlab_prog/create-a-cell-array.html

@Paul Barrette, Using Cell arrays is also the first alternative mentioned in the thread you have linked -

https://in.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval#answer_236124

Paul Barrette 2023-9-20

编辑：Paul Barrette 2023-9-20

A 3D array, as suggested by @Stephen23, was my first idea, but the arrays are of slightly different size. Cell arrays is the way to go - I've never used them, but now is the time. Thanks all. And sorry for not searching better and not providing adequate explanations (I wil do better next time).

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