renaming variable loaded from a file

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Reza S 2015-3-6

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编辑： Stephen23 2022-2-22

Hello, I have 4 .mat files including tens of variables of the same name. How I can rename the variables after loading each file in a new script file. I have read similar link but didn't work well.

Thanks

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Answer 1

Star Strider 2015-3-6

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Use either the load or matfile functions with an output argument. The structure format can keep the variable names separate.

For instance, if you have variable names ‘x’, ‘y’, and ‘z’ in each .mat file, you can load them all into your workspace without ambiguity. If your .mat files are named A.mat and B.mat, load them as:

A = load('A.mat');
B = load('B.mat');

then:

A.x         % ‘x’ from A.mat
B.x         % ‘x’ from B.mat

and so forth for the rest of them. You have to refer to them as such in the rest of your code, but they will be uniquely identified that way.

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Stephen23 2015-3-6

This might be useful too:

http://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

Star Strider 2015-3-6

My pleasure!

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Answer 2

Mingyang Sun 2022-2-22

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编辑：Mingyang Sun 2022-2-22

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use the command:

newname = struct2cell(load(filename)); newname=newname{1};

you don't even need to know the original variable name!

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Stephen23 2022-2-22

编辑：Stephen23 2022-2-22

在 MATLAB Online 中打开

That may be useful in the case of exactly one variable per file and very badly designed data (e.g. the variable is named the same as the file, or something similar), in which case the code should at least confirm that assumption:

C = struct2cell(load(filename));
assert(isscalar(C),'file must contain one variable only')
D = C{1};

However I would not recommend that approach as a solution to the original question ".. including tens of variables of the same name" because then you lose very important meta-information about those tens of variables (i.e. the variable names). For the original quetsion a much better approach would be to concatenate the imported data into one structure array, for example:

P = 'absolute or relative path to where the files are saved';
S = dir(fullfile(P,'*.mat'));
for k = 1:numel(S)
    F = fullfile(P,S(k).name);
    S(k).data = load(F);
end
A = [S.data] % <--- one structure array, with the original names of the variables.