How to derive a variable name from a variable?

How to derive a variable name from a variable?

A = [5 6 7 8];

B = ‘A’;

A(1) % this works and return the first element of A which is 5

B(1) % this doesn’t work like the code above

[Stephen23]

Start by reading this:

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

[Adam]

What exactly are you trying to do? It doesn't sound like a good plan - dynamic variable names are a very bad idea.

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

A = [5 6 7 8];
B = A;

A(1);
B(1);

would give you what you want from the perspective of the information you have given, that you simply want B(1) to return the same as A(1).

[Rightia Rollmann]

What I want to do is to access the first column and then the second column of a 5-by-7 matrix which is the value of a field named B. B is the third field of struct A. How can I do it dynamically best?

[Adam]

If B is a field of A why are you trying to create a variable B that represents the whole of A.

Just A.( 'B' ) would give what you want. Fields are not really ordered in a struct, at least not for general usage.

Answer 1

[Stephen23]

Although often loved by beginners, dynamically accessing variable names is not a robust, fast, or good way to write code. It makes code hard to read, slow, difficult to debug, and has other disadvantages too:

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

If you really need to access the names dynamically, then consider using a structure: it is fast and easy to access structure field names dynamically:

 S.A = [5,6,7,8];
 x = 'A';
 S.(x)

https://www.mathworks.com/help/matlab/matlab_prog/generate-field-names-from-variables.html

Answer 2

[Star Strider]

MATLAB does not recognise char(0145) and char(0146) as quotation marks in code.

A = [5 6 7 8];

B = 'A'                             % Sets ‘B’ TO Be Character ‘A’

B = A

B(1)

produces:

B =

A

B =

       5     6     7     8

ans =

       5

Answer 3

[Jan]

According to your comment, which is another problem than the original question:

A.B(:, 1:2)