Keeping record of Number of concatenated files

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ARN 2019-4-17

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编辑： Stephen23 2019-5-2

I am vertically concatinating some .mat files and i want to keep the track record of how many files i have concatinated;

Like putting 1 infront of values of file 1 (13780x1) and 2 infront of values of 2 (13840x1). Is there a way to do that?

Attached is the pic of random values; 3 files (15x1) concatinated so i want the left or the right answer.

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Adam Danz 2019-4-17

Stephen Cobeldick's solution does what you're asking.

Stephen23 2019-4-29

编辑：Stephen23 2019-4-29

"I am vertically concatinating some .mat files ..."

I doubt that: .mat files are a binary file format, it does not make much sense to concatenate them. You can certainly import their contents into MATLAB and concatenate those.

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Stephen23 2019-4-17

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编辑：Stephen23 2019-4-17

在 MATLAB Online 中打开

Inside your loop:

N = ... the total number of files.
C = cell(1,N)
for k = 1:N
    M = ... import the matrix here.
    M(:,end+1) = k;
    C{k} = M;
end
Z = vertcat(C{:})

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Stephen23 2019-4-29

编辑：Stephen23 2019-4-29

在 MATLAB Online 中打开

" i am missing your point."

Following exactly what I showed you in my answer, and assuming that each file contains an identically named matrix:

D = 'path of the directory where all files are saved';
S = dir(fullfile(D,'*.mat'));
N = numel(S);
C = cell(1,N);
for k = 1:N
    F = fullfile(D,S(k).name);
    fprintf('Reading %s\n',F);
    T = load(F); % structure
    M = T.nameOfMatrixInTheImportedStructureWhichYouHaveNotToldUs;
    M(:,end+1) = k;
    C{k} = M;
end 
Z = vertcat(C{:})

Note that this resolves your question about "i want to keep the track record of how many files i have concatinated..." but it does not tell you anything about the order that the files were imported in. For that you would need to pay careful attention to the filenames: depending on the filename formatting and the order you want they might need to be sorted before the loop:

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

EXTRA Another neat option is to skip the cell array altogether and use the structure S to store the data, which means that it contains both the file meta-data and the imported data:

D = 'path of the directory where all files are saved';
S = dir(fullfile(D,'*.mat'));
N = numel(S);
for k = 1:N
    F = fullfile(D,S(k).name);
    fprintf('Reading %s\n',F);
    T = load(F); % structure
    M = T.nameOfMatrixInTheImportedStructureWhichYouHaveNotToldUs;
    M(:,end+1) = k;
    S(k).matrix = M;
end 
Z = vertcat(S.matrix)

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

ARN 2019-5-2

Hi,

Thanks for the answer. Sorry for asking late, but this method is good for concatination of one matrix while i have got 30. That is why, i was creating the structure afterwards. Any suggestions on that...:)

Stephen23 2019-5-2

编辑：Stephen23 2019-5-2

" Any suggestions on that..."

Sure: using the code from my earlier comment, simply call fieldnames on T and then add a nested loop over those fields.

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

Then inside the nested loop add the extra column. After the nested loop allocate T to C.

Or, if you are feeling particularly adventurous, write something using structfun.

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