Creating variables in a foor loop using num2str

Hi,

title probably says it all. I want to create variables according to the i in the loop. I just don't even know if I can incorporate the function (I've already tried num2str, eval, evalc, sprintf) into variable definition. Below is a non-working code just to illustrate what I mean to do (hopefully). This example is just for 3 different variables but later on, I need to do this for about 60 more variables. I just cannot quite put my hand on the right formulation of the loop.

Thank you for any advices

%%% years_10 = [xvalues, yvalues]... n*2 matrices
years_10=readmatrix('10_years.csv');
years_20=readmatrix('20_years.csv');
years_30=readmatrix('30_years.csv');

for i=10:10:30
   years_num2str(i) = readmatrix(sprintf('%d_years.csv',i);
end

[Walter Roberson]

Why do you think this is necessary? Why not use a cell array instead?

[Stephen23]

The easy, simple, and very efficient approach is to use indexing into one array, e.g. a cell array or structure array.

Using indexing is shown in the MATLAB documentation:

https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

Answer 1

[William Rose]

@Jiri Kovar,

[edit: change "v" to "s" in my description, to match the code]

N=50;
for i=10:10:N, s.(strcat('a',num2str(i)))=i^2; end
disp(s)

    a10: 100
    a20: 400
    a30: 900
    a40: 1600
    a50: 2500

creates a structure s with fields a10, a20, ..., a50. Each one equals a scalar. You could initialize each one to be a vector or array, if you prefer.

[William Rose]

@Jiri Kovar, see this tutorial by @Steven Lord about why this is a bad idea.

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

[Walter Roberson]

@William Rose

The tutorial is by @Stephen23

[William Rose]

Thank you, @Walter Roberson and @Stephen23.

[Mady]

Thank you @William Rose for quite a handy solution. The tutorial about Dynamic variable naming is very useful, lots of new informations :)

[William Rose]

@Jiri Kovar, you're welcome.