How to generate m code for a variable

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Hui Li 2022-8-5

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https://ww2.mathworks.cn/matlabcentral/answers/1774855-how-to-generate-m-code-for-a-variable

评论： Walter Roberson 2022-8-8

I'd like to write a script to generate m code for variable in the work space.

For example I have a variable aa in the workspace.

I want to auto create a script called "parameter.m" which contains the following text:

The actual job I need to do is more complicated than this aa example. My workspace variable will be larger in dimension and I'll have 4-5 different variables to generate. Is there a way to do achieve this?

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Answer 1

Walter Roberson 2022-8-5

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在 MATLAB Online 中打开

If the variable is double precision and is at most 2 dimensions, then you can use mat2str to construct the right hand side

aa = magic(5)
aa = 5×5
    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9
mat2str(aa)
ans = '[17 24 1 8 15;23 5 7 14 16;4 6 13 20 22;10 12 19 21 3;11 18 25 2 9]'

If it is numeric and at most 2 dimensions but is a different data type, then you can use mat2str() but you would have to insert the type conversion yourself.

If it is numeric but more than 2 dimensions, then unfortunately there is no Mathworks routine that will automatically build the required cat() calls to put together 2d slices in an appropriate way.

For numeric with more than 2 dimension, or for structures or cell arrays, you might want to consider jsonencode

bbb = reshape(magic(6), 2, 3, []);
jsonencode(bbb)
ans = '[[[35,1,6,26,19,24],[31,9,2,22,27,20],[30,5,34,12,14,16]],[[3,32,7,21,23,25],[8,28,33,17,10,15],[4,36,29,13,18,11]]]'

The string produced is not MATLAB code itself, but it is something you could wrap in a jsondecode call.

Is the point to automatically generate MATLAB-language code, or is the point to generate something that, when executed, gives you back a replica of the original?

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Hui Li 2022-8-8

Hi Walter thanks a lot for your suggestions! The end goal is to generate Matlab-language code in the form of m script. I'll try the mat2str and jsonencode command you suggested.

Walter Roberson 2022-8-8

The question becomes whether what is generated needs to be distinctly MATLAB code, human readable as MATLAB code (whether for review purposes or to allow easy editing) -- or whether it just needs to be something that when executed gives back a clone of the original data. And, of course, which kinds of variables this will be limited to.

For example if it is applied to a figure, then does it need to generate all of the graphics calls needed to recreate the figure? And if so, then if a figure with that number already exists then should it operate on that figure or should it create a new figure.

Recreating something like an open TCP connection or a parpool data queue might not be feasible.

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