How to read multiple matrices separately from .txt file

Here is a .txt file like

matrixdata

matrix1
BEGIN
111
111
.
.
.
111
END

matrix2
BEGIN
222
222
222
.
.
.
222
END

There are several matrices and each is between "BIGIN" and "END" string.

I tried reading this by using "readmatrix" function.

Then, matrices were combined and read as one matrix like

111
111
.
.
.
111
222
222
222
.
.
.
222

Is there any good way to read matrices separately for every "BIGIN" and "END"?

Answer 1

[Karim]

Since it's not clear whether or not these matrices have the same dimensions, you can try to save them in a cell array.

See below for some example code, hope it helps

Best regards

% link to the text file
fileID = fopen('MatrixExample.txt'); 
% read the whole file, interpret each line as a string
MyText = textscan(fileID, '%s%[^\n\r]', 'Delimiter', '', 'WhiteSpace', '',  'ReturnOnError', false);

% first the start locations
StartLineIdx = cellfun(@(x) contains(x, "BEGIN"),MyText(:,1),'uni',0);
StartLineIdx = find(StartLineIdx{1}) + 1;

% now find the stop locations of each data block
StopLineIdx = cellfun(@(x) contains(x, "END"),MyText(:,1),'uni',0);
StopLineIdx = find(StopLineIdx{1}) - 1;

% Allocate the cell array
MyData = cell(numel(StartLineIdx),1);

% Get the data
for i = 1:numel(StartLineIdx)
    MyData{i} = cellfun(@(x) textscan(x,'%f','Delimiter', '\t','WhiteSpace','', 'ReturnOnError',false),MyText{1}(StartLineIdx(i):StopLineIdx(i)));
    MyData{i} = cellfun(@transpose,MyData{i},'UniformOutput',false);
    MyData{i} = cell2mat(MyData{i});
end
Matrix_1 = MyData{1} % this is the first matrix

Matrix_1 = 3×2

111 112 111 116 111 112

Matrix_2 = MyData{2} % this is the second matrix

Matrix_2 = 4×1

222 222 222 222

[亮介 桶谷]

Thank you for your kind answer.

It works well.

I also wonder when the matrix is two dimensional with tab delimiter.

That's the reason why I used "readmatrix" function.

Any solution?

Best Regards

[Karim]

Yes, however the code becomes a bit more complicated.

I updated the example text file and also the code in the answer.

[亮介 桶谷]

It works well for 2d matrix!!!

Thank you for your kind cooperation!!