Keeping record of Number of concatenated files

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.

[Adam Danz]

Isn't that what your column #3 is doing?

[ARN]

i did it manually in excel? Need a method to do that in MATLAB.

[Adam Danz]

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

[Stephen23]

"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.

Answer 1

[Stephen23]

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{:})

[ARN]

I am sorry, i donot understand the line "import the matrix here" . I am concatinating the following files."

[Stephen23]

'i donot understand the line "import the matrix here"'

You did not upload any sample files, nor explain anything about the content (e.g. variable names, variable sizes, variable classes, etc), so I could not guess what you needed to do to import data that you had told us nothing about. Your screenshot apparently shows the fields of a nested structure, but it is not clear how this relates to your question.

[ARN]

So i made a structure of all the available variables which my file contains (as they are time series). And i am concatinating every field; for seven files one variable(field) firstMRR... there are seven cells containg more than 2700 values each; considering only this field how will i tell that index 7465 contains the value of third file.

[Stephen23]

"how will i tell that index 7465 contains the value of third file."

I would just use the code in my answer.

[ARN]

% Get a list of matData files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.mat'); % get all the .mat files
matFiles = dir(filePattern);
for k = 1:length(matFiles)
  baseFileName = matFiles(k).name;
  fullFileName = fullfile(myFolder, baseFileName);
  fprintf(1, 'Now reading %s\n', fullFileName);
  matData(k) = load(fullFileName); 
  %matData(:,end+1)= k;
end 

i am sorry, this is the code, i am missing your point. Can you please add into that?

[Stephen23]

" 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

[Adam Danz]

+1 for the 'neat' structure option. Nice and tidy.

[ARN]

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]

" 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.