read txt file contains multiple arrays with different sizes

hi I have a txt file contains a 1D matrix and 2- 2D matrices, they are separated by new line. morover, the 2D matrices elements are separated by space how I read these matrices and put them in three arrays or cells

[Guillaume]

You need to provide more details (e.g. how do you find the end of the first 2D matrix) or even better attach a sample file.

Answer 1

[Prateekshya]

Hello Amal,

To read a text file containing a 1D matrix and two 2D matrices separated by new lines and spaces, you can use MATLAB's file I/O functions. Let us consider this example file:

File name: data.txt

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

1 2 3

4 5 6

7 8 9

10 11 12

13 14 15

16 17 18

The below steps can be followed for reading the above file:

• Use "fopen" to open the file.
• Use "fgetl" to read lines from the file.
• Use "str2num" to convert string lines to numeric arrays.
• Store the 1D matrix in a vector.
• Store the 2D matrices in separate arrays or cell arrays.

Here is a MATLAB script to achieve this:

% Open the file
fileID = fopen('data.txt', 'r');
if fileID == -1
    error('File could not be opened.');
end

% Initialize variables
matrix1D = [];
matrix2D_1 = [];
matrix2D_2 = [];
currentMatrix = 1;
tempMatrix = [];

% Read the file line by line
while ~feof(fileID)
    line = fgetl(fileID);
    
    % Check if the line is empty (new line)
    if isempty(line)
        % Store the temporary matrix into the appropriate variable
        if currentMatrix == 1
            matrix1D = tempMatrix;
        elseif currentMatrix == 2
            matrix2D_1 = tempMatrix;
        elseif currentMatrix == 3
            matrix2D_2 = tempMatrix;
        end
        
        % Reset the temporary matrix and increment the current matrix counter
        tempMatrix = [];
        currentMatrix = currentMatrix + 1;
    else
        % Convert the line to a numeric array
        numericLine = str2num(line); %#ok<ST2NM>
        
        % Append the numeric array to the temporary matrix
        tempMatrix = [tempMatrix; numericLine];
    end
end

% Store the last matrix (if any)
if currentMatrix == 1
    matrix1D = tempMatrix;
elseif currentMatrix == 2
    matrix2D_1 = tempMatrix;
elseif currentMatrix == 3
    matrix2D_2 = tempMatrix;
end

% Close the file
fclose(fileID);

% Display the results
disp('1D Matrix:');
disp(matrix1D);
disp('2D Matrix 1:');
disp(matrix2D_1);
disp('2D Matrix 2:');
disp(matrix2D_2);

The code can be modified according to the requirement. I hope this helps!

Thank you.