How to find mean from different variables in work space

Question

Safi ullah 2017-12-6

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https://ww2.mathworks.cn/matlabcentral/answers/371381-how-to-find-mean-from-different-variables-in-work-space

评论： Safi ullah 2017-12-6

Hello, everyone I have 91 variables in workspace. The size of all variables is same e.g

Z1=133×8
Z2=133×8
Z3=133×8
.........
.........
Z91=133×8

I am trying to find the mean of rows (35-36) for each variable by using for loop given below

for i=1:91;
answer=mean(zi(35:36,:));
end

but it does not work. Any guidance will be appreciated. Thanks

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Stephen23 2017-12-6

编辑：Stephen23 2017-12-6

The simplest solution is do not have 90 variables in your workspace and then try to perform calculations on them all. MATLAB is really efficient when operating on arrays, and if you had just one array then all you would need is one call to mean. How simple can it get?

If you get all of variables by importing some data then import them into one ND array and your task will be trivial to solve. Currently you have a task that can only be solved by writing ugly, complex, slow, buggy, hard-to-debug code.

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Answer 1

KL 2017-12-6

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/371381-how-to-find-mean-from-different-variables-in-work-space#answer_294947

在 MATLAB Online 中打开

why do you have 91 variables named sequentially in the workspace? Why not use a 3D matrix?!

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

You only need one variable called Z.

Z = rand(133,8,91);

then to calculate mean, all you need is one line,

Z_m = mean(A(35:36,:,:))

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Jan 2017-12-6

+1. Of course. Using "Z1, Z2, ..." is the problem. As soon as a cell array or multi-dimensional array is used, the calculation of the mean gets trivial.

Safi ullah 2017-12-6