Storing Matrix in Workplace on each iteration

Hello community,

This code uses a custom importfile function to get specific columns from .txt files and it works fine.

How can I extend the for loop so that the code:

a) saves a matrix(i) on each iterration as a value in the workplace

b) calculates the by element mean of all these matrices in a new matrix

files = dir('*.txt'); %get all text files of the present folder
N = length(files);  %Total number of files
for i = 1:N
   filename = files(i).name ;
   A=importfile(files(i).name);
   A=A{:,:}; %Convert the table into matrix
end

Thank you for your support!

V.

Answer 1

[Adam Danz]

"How can I ... a) saves a matrix(i) on each iterration as a value in the workplace"

What I think you mean is to store each iteration of "A". Correct me if that's incorrect. The variable "A" is already stored in the workspace but you're overwriting it upon each iteration of the i-loop.

Below are 2 options.

Option 1: store each matrix in a cell array

% Create a cell array that will store your matrices
Amat = cell(size(files)); 
for i = 1:N
   A=importfile(files(i).name);
   Amat{i} = A{:,:}; % <---- store the matrix in the cell array 
end

Option 2: if the matrices are all the same size, store them in a 3D array

Amat = nan(m,n,numel(files));  %where m and n are the expected dimension of the matrix
for i = 1:N
   A=importfile(files(i).name);
   Amat(:,:,i) = A{:,:}; % <---- store the matrix in a 3D array
end

"How can I... b) calculates the by element mean of all these matrices in a new matrix"

If you want the element-wise mean of each matrix (assuming they are all the same size),

% IF YOU CHOSE OPTION 1 ABOVE
% Assumes Amat has 1 row and f columns
[m,n] = size(Amat{1}); 
f = numel(Amat); 
AmatMean = mean(reshape(cell2mat(Amat'),m,n,f),3); 


% IF YOU CHOSE OPTION 2 ABOVE
AmatMean = mean(Amat,3);

[Vladimir Palukov]

Thnaks for your quick reply!

Since the matrices are the same size option 2 worked like charm :)

[Adam Danz]

Good choice!