How can add a name of table by concatenating strings?

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Zeynab Mousavikhamene
编辑： Stephen23 2020-2-6
I have multiple matlab tables that at first I need load them to the matlab and then do some analysis. Assume they are saved with these names: tableA, tableB, tableC. I am interested to load all in one array by defining the name of tables in one array:
A=['tableA','tableB','tablesC']
so that I can write a for loop to load all arrays instead of writing load for each individual table. Sth like:
for i=1:size(A)
load(A(i))
end
and it wont work because A(i) are strings not the name of tables.
How can I solve this issue?
It is more genreal question. It happens to me in many cases that I need to make the name of table by strcat function.
How can I do that?
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BN
BN 2020-1-31
编辑：BN 2020-1-31
I'm not sure why you require to do this because TUTORIAL: Why Variables Should Not Be Named Dynamically (eval) you can probably fix your problem by store all your tables in a cell array.
D = 'D:\whatever'; % select directory
filePattern = fullfile(D, '*.mat'); %or if you have .xlsx tables
file = dir(filePattern);
x = {};
for z = 1 : numel(file)
baseFileName = file(z).name;
fullFileName = fullfile(D, baseFileName);
x{z} = load(fullFileName); %or readtable if you have .xlsx tables
fprintf('read file %s\n', fullFileName);
end
then you can simply access each table using something like:
mytable = x(:,1)
let me know if it worked for you !
Stephen23
Stephen23 2020-2-1
"It happens to me in many cases that I need to make the name of table by strcat function."
Forcing numbers or any other meta-data into variable names is a sign that you are doing something wrong:
https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
"How can I solve this issue?"
Use arrays and indexing. You can trivially load into an output variable (which is a scalar structure):
S = load(...);
and then use indexing to allocate that array to a non-scalar structure or a cell array... and is exactly what the MATLAB documentation recommends:
https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

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Walter Roberson
Walter Roberson 2020-1-31
Don't do that!
filenames = something appropriate ;
nfiles = length(filenames);
tcell = cell(nfiles, 1);
for k=1:nfiles
filestruct = load(filenames{k});
fn = fieldnames(filestruct);
tcell{k} = filestruct.(fn{1});
end
A = vertcat(tcell{:}) ;
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Walter Roberson
Walter Roberson 2020-2-6
Hmmm, my code does not add dynamic names to the structure, or at least not deliberately, but I guess it would not be completely wrong to argue that the way I use load() is a use of dynamic field names. MATLAB automatically creates the field names in that case, rather than my deliberately creating them. I read from them rather than writing to them. If the variable names in the file were fixed then even this would not be needed.
Stephen23
Stephen23 2020-2-6
编辑：Stephen23 2020-2-6
"I wanted to make dynamic name for the table which is not recommended."
Correct: accessing variable names dynamically is not recommended by experienced MATLAB users, and is also very clearly discouraged by the MATLAB documentation:
https://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html
"Walter's code add dynamic name to structure not directly to the table (which is not recommended)."
I don't see that advice anywhere in the MATLAB documentation. While it is certainly possible to misuse dynamically named fields (e.g. where a non-scalar structure with indexing would be simpler and more effiicient) in general I see no reason to avoid them, especially in your case when it is the much better option.
Most of the risks/disadvantages to dynamically naming variables, such as those I list here:
https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
do not apply to dynamically named fields, perhaps efficiency could be relevant.

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