Using assignin or evalin command to populate Structure Elements with Numeric Data.

Question

Shyama Prasad Mishra 2015-6-24

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https://ww2.mathworks.cn/matlabcentral/answers/225148-using-assignin-or-evalin-command-to-populate-structure-elements-with-numeric-data

编辑： Stephen23 2015-6-29

采纳的回答： Azzi Abdelmalek

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Hello,

I am getting an error while executing the below command:

assignin('base', 'A.B', 1)|

Error:

??? Error using ==> assignin

Invalid variable name "A.B" in ASSIGNIN.

As a work around i tried to use:

assignin('base', 'temp', 1);
evalin('base','A.B = temp');
evalin('base','clear temp');

The above work around was proposed in one of the previous threads:

http://www.mathworks.com/matlabcentral/newsreader/view_thread/26671

The problem I have is that, my Structure elements are read from a Cell Array inside a for loop.

Lets say C = {'A.B', 'A1.B1'}

So how do I pass 'C' as a parameter to the below line:

evalin('base','C = temp')

Expected output: A.B = 1, A1.B1 = 1 (In Base Workspace)

I also tried to use setfield command, but could not succeed.

Thanks, Shyama

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Stephen23 2015-6-25

编辑：Stephen23 2015-6-29

The best answer is to avoid doing this at all... and use more robust methods of passing values between workspaces:

http://www.mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html

http://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html

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

http://www.mathworks.com/matlabcentral/answers/225435-save-variable-as-string-from-user-input

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Answer 1

Azzi Abdelmalek 2015-6-24

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https://ww2.mathworks.cn/matlabcentral/answers/225148-using-assignin-or-evalin-command-to-populate-structure-elements-with-numeric-data#answer_183840

编辑：Azzi Abdelmalek 2015-6-24

在 MATLAB Online 中打开

You probably can use other alternatives here http://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html

For your problem you can use

C  = {'A.B', 'A1.B1'}
assignin('base', 'temp', 1);
cellfun(@(x)  evalin('base',[x  '=temp']),C)

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Shyama Prasad Mishra 2015-6-25

Thanks! Works Perfectly.

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Answer 2

Matt J 2015-6-24

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https://ww2.mathworks.cn/matlabcentral/answers/225148-using-assignin-or-evalin-command-to-populate-structure-elements-with-numeric-data#answer_183842

在 MATLAB Online 中打开

Not sure why you're not just using setfield(), but another option is

evalin('base','A.B=1');

or

evalin('base',['A.B=' num2str(1)]);

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Shyama Prasad Mishra 2015-6-25

编辑：Shyama Prasad Mishra 2015-6-25

Hi Matt,

I am not using set field because A.B can be any string.

I tried evalin('caller',['setfield(A,''B'',10)']), which works.

How ever when I try to pass the structure name as a string, it does not work.

For Example: C = 'A'; evalin('base',['setfield(C,''B'',10)']) gives an output C.B = 10.

Where as I want the output to be A.B = 10

Am I using Setfield wrongly?

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Using assignin or evalin command to populate Structure Elements with Numeric Data.

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