Is it possible to set a variable by its name?

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Mr M.
Mr M. on 10 Jun 2015
Edited: Stephen23 on 19 Jun 2019
I would like to make a for cycle, but the running variable should be defined by the user. For example:
params = [1,2,5,7,13]
for i=1:length(params)
v = params(i);
% or x = params(i);
% or y = params(i);
end
So v, x, or y should be choosen by its name, for example from the information contained in a string: my_string = 'v';
  1 Comment
Stephen23
Stephen23 on 10 Jun 2015
Edited: Stephen23 on 10 Jun 2015
Use Ingrid's solution (a switch statement) or a structure with dynamic field names, or perhaps a non-scalar structure, or even functions (making internal operations independent from the input variable names). All of these would be much more robust than using dynamic variables.
Do not create variables dynamically, because this is a really bad programming practice that is buggy, slow, and removes lots of inbuilt code checking, amongst other disadvantages...
Although beginners seem to love variables magically popping in and out of workspaces, if you learn to not create dynamically named variables and instead use more robust programming practices then your code becomes much more reliable.

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Answers (2)

Ingrid
Ingrid on 10 Jun 2015
you can use a switch - case statement
for i = 1:length(params)
switch my_string
case 'v'
v = params(i);
case 'x'
x = params(i);
case 'y'
y = params(i);
otherwise
error('Unrecognized string name');
end
end
  1 Comment
Mr M.
Mr M. on 10 Jun 2015
Yes, switch is a possible solution, but lot of space and coding, and very rigid. It would be nice to make it automatically instead of writing down all variable names at least twice.

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Stephen23
Stephen23 on 10 Jun 2015
Edited: Stephen23 on 19 Jun 2019

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