Loop different variables from workspace

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Mariana 2019-12-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/496876-loop-different-variables-from-workspace

编辑： Stephen23 2019-12-16

num = 1; -------> 475
current_file = Test_1; -----------------> test_475    (Table of name 'Test_1' in workspace)
rate = height(current_file);
for i=1:rate
    rel = current_file.S;
    vel = current_file.E;
    time = current_file.t;
    Target_v{i,1} = rel(i) + vel(i);
    
    if i == rate
        T = array2table(Target_v);
        C = [current_file(:,1:3) T current_file(:,4:45)]
        eval(['Dataset_' num2str(num) '= C']);
        Target_v= [ ];
    end
end

I want to load multiple variables that are in workspace in a for loop add a column to each one of them and save them with another name or export them to excel. How can I do this?

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Stephen23 2019-12-16

"I want to load multiple variables that are in workspace in a for loop..."

If they are already in the workspace then they have already been loaded (unless you wrote out all of those names by hand), so most likely the best choice would be to simplify your code and load the data into one array (e.g. a cell array, a structure, a table, etc.).

Note that having many numbered variables is a sign of badly designed data.

"...add a column to each one of them and save them with another name or export them to excel."

Easy with basic indexing into one variable.

Mariana 2019-12-16

mat = dir('*.mat');

for q = 1:1

load(mat(q).name); I load the first mat file from a struct

----- it load all the tables in the workspace, but how do I modify each one of them? without using sprintf or eval.

end

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Answer 1

Stephen23 2019-12-16

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/496876-loop-different-variables-from-workspace#answer_406599

编辑：Stephen23 2019-12-16

在 MATLAB Online 中打开

The most important thing is to always load into an output variable:

Q = load(...) % Q is a scalar structure

where the fields of Q contain the variables from the .mat file. From there it is easy to access the fields using dynamic fieldnames:

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

As a special case, if each .mat file contains exactly one variable (e.g. a table) each with a different name, then you can use struct2cell quite effectively:

D = 'C:\Users\yourname\yourwork'; % absolute/relative path to where the files are saved
S = dir(fullfile(D,'*.mat')); 
for k = 1:numel(S)
    Q = load(fullfile(D,S(k).name));
    C = struct2cell(Q);
    T = C{1}; % T will be your table
    ... do whatever you want with T, 
    ... then save it in a CSV file:
    F = fullfile(D,sprintf('newfile_%d.csv',k));
    writetable(T,F)
    ... or store it for accessing after the loop:
    S(k).table = T;
end