Matlab: In for loop, change name of variable

Question

Nafalai 2021-11-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1594664-matlab-in-for-loop-change-name-of-variable

评论： Nafalai 2021-11-24

Hi!

I have a variable (vector of size 101x1) in a for loop, named input_reec_PGC1. It is imported from the input_consigne_egal_mesure; on the second line of my code (below).

I define another variable (also vector 101x1), named new_input. Now, I would like to write input_reec_PGC1 = new_input.

My code below works, however, I would like for the input_reec_PGC1 to be programatically generated, from the variable nom_parametre_variant (4th line of code), as I did for the variable variation_du_parametre (5th line of code).

Indeed, I need to do a large number of simulations and the less I need to change my code the better, so I would like the user only to have to write down the nom_parametre_variant and from there the code does the rest.

I tried

eval(['input_', nom_parametre_variant ]) = new_input;

but get the error:

In an assignment A(I) = B, the number of elements in B and I must be the same.

I have the following code:

clear;
input_consigne_egal_mesure;
variation_parametres;    
nom_parametre_variant = 'reec_PGC1';
variation_du_parametre = eval(['var_',nom_parametre_variant]);
name_output_file = [nom_parametre_variant, '.csv'];
name_output_folder = char(['results_',nom_parametre_variant]);
if ~exist(name_output_folder, 'dir')
    mkdir(name_output_folder)
end
% pwd: current path 
path_to_results_folder = [pwd,'/',name_output_folder];
path_to_output_file = fullfile(path_to_results_folder, name_output_file);
solutions = zeros(1000,length(var_VGO)*4);
colonne = 1;
for i = 1 : numel(variation_du_parametre);
    % On change le parametre variant
    disp(['Variation: ',num2str(variation_du_parametre(i))]);     
    %% ISSUE HERE
    % new_input = variation_du_parametre(i) * ones(1, length(t));
    input_reec_PGC1 = variation_du_parametre(i) * ones(1, length(t));
    input_reec_PGC1 = new_input;
    %%
    
    options = simset('SrcWorkspace','current') ;
    sim('mon_modele_INES.slx',temps_simulation, options);
    solutions(:, colonne:1:colonne+3)=yout;
    colonne = colonne + 5;
end

Thank you in advance for your help!

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Answer 1

Jan 2021-11-24

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1594664-matlab-in-for-loop-change-name-of-variable#answer_839349

This is a very bad idea. The severe problems caused by the dynamic creation of variables have been discussed in the forum exhaustively. See: TUTORIAL: Eval