Is there any way to access a variable whose name is expressed by another string variable?

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Daiki 2021-8-2

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评论： darova 2021-8-5

Is there any way in MATLAB to access a variable whose name is expressed by another string variable?

for example, when

myvar = 10;

string_myvar = "myvar";

were in the workspace and substituting the numerical scalar myvar into another myvar2 as

myvar2 = myvar;

Id’ like to find a way to give the right hand side "as the content of string scalar ‘string_myvar’ ".

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Daiki 2021-8-5

编辑：Daiki 2021-8-5

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I have a further question. In an originally defined function

function varargout = myfun(varargin)

a vector which defines a set of output variable and their order for varargout as

myargout = ["arg1", "arg2", "arg3"];

With this expression, I intend varargout{1} is for arg1. After some calculation, I substitute function output as

varargout{find(strcmp("arg1",myargout))} = arg1;
varargout{find(strcmp("arg2",myargout))} = arg2;
varargout{find(strcmp("arg3",myargout))} = arg3;

but in this way, I need to modify this substitution part every time the contents of myargout is changed, because (of course) the string "arg1" and a variable name arg1 are not related. For instance, if I change its contents to

myargout = ["arg1", "arg3", "arg4"];

(from "arg2" to "arg3" for the second variable of varargout, and from "arg3" to "arg4" for the third), then I need to change the substitution part as

varargout{find(strcmp("arg1",myargout))} = arg1;
varargout{find(strcmp("arg3",myargout))} = arg3;
varargout{find(strcmp("arg4",myargout))} = arg4;

where statement for arg2 is deleted and arg4 is added. What I want to do is automatize this substitution part, by only changing myargout.

Is there a good way for this?

I thought indexing was difficult to apply.

Stephen23 2021-8-5

编辑：Stephen23 2021-8-5

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Get rid of FIND: logical indexing is simpler.

The robust and efficient approach would be to put all of the variables into one container array (e.g. structure, cell array, table) and then use ISMEMBER or dynamic fieldnames or something similar to select the ones for the output.

For example:

C = {arg1,arg2,..,argN};
N = {'x1','x2',..,'xN'};
userwants = ["x1","x3"];
[X,Y] = ismember(userwants,N);
assert(all(X),'no match')
varargout = C(Y)

Daiki 2021-8-5

@Stephen Cobeldick Thank you for the good approach, and it works well !

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Chunru 2021-8-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/890397-is-there-any-way-to-access-a-variable-whose-name-is-expressed-by-another-string-variable#answer_761312

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myvar = 10;
string_myvar = "myvar2"; 
assignin('base', string_myvar, myvar);
myvar2
myvar2 = 10

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Stephen23 2021-8-5

Or we could show beginners how easy it is to write simpler, neater, more robust, more efficient code:

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

darova 2021-8-5

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