Matrix Maipulation and adding from variables in the workspace

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arun Dhillon 2019-5-9

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https://ww2.mathworks.cn/matlabcentral/answers/461192-matrix-maipulation-and-adding-from-variables-in-the-workspace

评论： arun Dhillon 2019-5-13

I am saving a file(penmax), which has n no. of variables. In each variable, the size is always 1*5 (1 row, 5 cols.); the names of variables are liuke pick1, pick2,pick3...but the the no of variables inside the penmax file changes each time i run the script.

What I want to do is, to save all the variables inside of the penmax file into an m*5 matrix(newmatrix). I cannot use [] to concatenate each variable with the other one as I am not sure for how many variables penmax may have in total; but I am sure for each of the variables will have 1 row and 5 cols. Please edify me for how can I put all the variables of penmax into an n*5 matrix(newmatrix).

The file format is penmax.mat

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Stephen23 2019-5-10

编辑：Stephen23 2019-5-10

"Essentially lets say, you simply variabes in the workspace from a1,a2,...aN. "

I would never have numbered variables like that in my workspace, so that question is moot.

Having numbered variables is a sign that code is very badly designed. Usually what happens with numbered variables is that beginners try to access them dynamically by name. Dynamically accessing variable names is one way that beginners force themselves into writing slow, complex, obfuscated, buggy code that is hard to debug. Read this to know why:

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

Avoiding such badly design code is very easy, usually using one array and some indexing is all that is required. Indexing is simple, neat, easy to debug, and very efficient (unlike what you are trying to do).

I doubt that you sat and wrote all of those variable names out by hand, so wherever you imported/generated those arrays, instead simply allocate them into one (preallocated) array (which could be numeric, cell, structure, table, etc.):

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

arun Dhillon 2019-5-13