Matrix insertion to a txt-file

Question

Robert Bag 2021-5-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/830028-matrix-insertion-to-a-txt-file

评论： Adam Danz 2021-5-20

I am trying to get matlab to put three matrices into a text file, in a nice fashion.

I have this code:X = randi(10,3,5);

dlmwrite('Mymatrices.txt',X)
Y = randi(10,5,7);
dlmwrite('Mymatrices.txt',Y,'-append')
Z = randi(10,20,2);
dlmwrite('Mymatrices.txt',Z,'-append')
clear
%dlmwrite'Mymatrices.txt')
readmatrix('Mymatrices.txt')
save('Matlab283workspace.mat')

BUT I would like to modify it to :

Put the matrices in a nicer fashion in the text file, and without the commas.
Let each matrix be preceeded by the information:size, above the matrices , in the text-file
When i write "readmatrix" at the end, it only writes out the last matrix - allthough all three matrices are present in the txt-file

Thanks for input!

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Adam Danz 2021-5-14

在 MATLAB Online 中打开

Robert Bag's answer moved here as a comment

Whats wtrong with this code_

X = randi(9,3,5);
txt1 = ['First matrix dimensions: ' num2str(size(X,1)) ' by ' num2str(size(X,2))];
writematrix(txt1,'Mymatrices.txt','delimiter', ' ')
writematrix(X,'Mymatrices.txt','delimiter',' ','append')
Y = randi(9,5,7);
txt2 = ['Second matrix dimensions: ' num2str(size(Y,1)) ' by ' num2str(size(Y,2))];
writematrix(txt2,'Mymatrices.txt','delimiter',' ', 'append')
writematrix(Y,'Mymatrices.txt','delimiter',' ', 'append')
Z = randi(9,20,2);
txt3 = ['Third matrix dimensions: ' num2str(size(Z,1)) ' by ' num2str(size(Z,2))];
writematrix(txt3,'Mymatrices.txt','delimiter',' ', 'append')
writematrix(Z,'Mymatrices.txt','delimiter',' ','append')
clear
%dlmread('Mymatrices.txt')
save('Matlab283workspace.mat')

I get this:

Error using writematrix (line 191)
Wrong number of arguments. A filename must be provided when supplying additional parameters, and each
parameter name must be followed by a value.
Error in Matlbabwritematrix281 (line 4)
writematrix(X,'Mymatrices.txt','delimiter',' ','append')

Robert Bag 2021-5-14

编辑：Adam Danz 2021-5-14

在 MATLAB Online 中打开

This gets me everything but retreiving "back" my information from the txt-file.

X = randi(9,3,5);
txt1 = ['First matrix dimensions: ' num2str(size(X,1)) ' by ' num2str(size(X,2))];
writematrix(txt1,'Mymatrices.txt','delimiter',' ')
writematrix(X,'Mymatrices.txt','delimiter',' ','WriteMode','append')
Y = randi(9,5,7);
txt2 = ['Second matrix dimensions: ' num2str(size(Y,1)) ' by ' num2str(size(Y,2))];
writematrix(txt2,'Mymatrices.txt','delimiter',' ','WriteMode','append')
writematrix(Y,'Mymatrices.txt','delimiter',' ','WriteMode','append')
Z = randi(9,20,2);
txt3 = ['Third matrix dimensions: ' num2str(size(Z,1)) ' by ' num2str(size(Z,2))];
writematrix(txt3,'Mymatrices.txt','delimiter',' ','WriteMode','append')
writematrix(Z,'Mymatrices.txt','delimiter',' ','WriteMode','append')
clear
type('Mymatrices.txt');
save('Matlab283workspace.mat')

Adam Danz 2021-5-20

@Robert Bag you've got 13 questions, all of which have at least one answer, but you've never accepted any of them. Your questions are interesting and it looks like you've received a lot of help. Please take the time to accept answers that pointed you in the right direction. See link.

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Answer 1

Mathieu NOE 2021-5-14

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/830028-matrix-insertion-to-a-txt-file#answer_699793

在 MATLAB Online 中打开

hello Robert

try this :

clc
clearvars
dlmwrite('Mymatrices.txt','----------------------','delimiter','')
X = randi(10,3,5);
txt1 = [' First matrix dimensions  : ' num2str(size(X,1)) ' by ' num2str(size(X,2))];
dlmwrite('Mymatrices.txt',txt1,'delimiter','','-append')
dlmwrite('Mymatrices.txt',X,'delimiter','\t','-append')
dlmwrite('Mymatrices.txt','----------------------','delimiter','','-append')
Y = randi(10,5,7);
txt2 = [' Second matrix dimensions : ' num2str(size(Y,1)) ' by ' num2str(size(Y,2))];
dlmwrite('Mymatrices.txt',txt2,'delimiter','','-append')
dlmwrite('Mymatrices.txt',Y,'delimiter','\t','-append')
dlmwrite('Mymatrices.txt','----------------------','delimiter','','-append')
Z = randi(10,20,2);
txt3 = [' Third matrix dimensions : ' num2str(size(Z,1)) ' by ' num2str(size(Z,2))];
dlmwrite('Mymatrices.txt',txt3,'delimiter','','-append')
dlmwrite('Mymatrices.txt',Z,'delimiter','\t','-append')
dlmwrite('Mymatrices.txt','----------------------','delimiter','','-append')
clear
%dlmwrite'Mymatrices.txt')
readmatrix('Mymatrices.txt')
save('Matlab283workspace.mat')

will give this output :

----------------------

First matrix dimensions : 3 by 5

10 10 8 9 8

1 10 1 9 4

10 7 2 2 3

----------------------

Second matrix dimensions : 5 by 7

9 10 10 7 6 9 1

5 4 4 3 9 3 6

7 6 7 6 10 10 5

1 8 5 2 8 10 1

8 2 7 10 6 10 10

----------------------

Third matrix dimensions : 20 by 2

8 3

1 10

8 2

3 9

10 5

2 8

6 4

5 9

9 2

3 7

6 2

10 5

7 6

1 6

4 8

9 8

4 10

8 5

----------------------

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Robert Bag 2021-5-14

But I just wonder then how a I can do that it will write out alll three matrices from the txt-file when using the readmatrix?

Adam Danz 2021-5-14

+1, simple and effective.

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Answer 2

Adam Danz 2021-5-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/830028-matrix-insertion-to-a-txt-file#answer_699828

编辑：Adam Danz 2021-5-14

在 MATLAB Online 中打开

Another way to do this is by using formattedDisplayText() which became available in Matlab R2021a (see Community Highlight).

Collect all of the text in a string array.

The string array will be vertically concatenated.

X = randi(10,3,5);
Y = randi(10,5,7);
Z = randi(10,20,2);
clear('txt')
txt(1) = "----------------------";
txt(2) = string(sprintf(' First matrix dimensions  : %d by %d', size(X)));
txt(3) = formattedDisplayText(X);
txt(4) = txt(1); 
txt(5) = string(sprintf(' Second matrix dimensions  : %d by %d', size(Y)));
txt(6) = formattedDisplayText(Y);
txt(7) = txt(1); 
txt(8) = string(sprintf(' Third matrix dimensions  : %d by %d', size(Y)));
txt(9) = formattedDisplayText(Z);
txt(10) = txt(1); 

Join the string array into a single string

% Remove any new-line characters from the formattedDisplayText outputs
txt = regexprep(txt,'\n$', '');
% Join string array into single string
txtCat =  strjoin(txt(:),newline)
txtCat = 
    "----------------------
      First matrix dimensions  : 3 by 5
          9     8     9     1     7
          7     9     7     6     1
          7    10     5     9    10
     ----------------------
      Second matrix dimensions  : 5 by 7
          1     5     7     2     9     8     8
          4     3     9     2     8     9     6
          2     7     3     1     9     8     5
          7     4     3     3     4     5     3
          4     4    10     1     9     3    10
     ----------------------
      Third matrix dimensions  : 5 by 7
          8    10
          1     8
         10     5
         10     5
         10     7
          1     4
          1    10
          8     7
          4     3
          1     7
          1     2
          6     7
          5     1
          4     2
          7     8
          9     5
          2     7
         10     4
          4     2
          1     4
     ----------------------"

Write string to text file

This example writes to the temporary directory. Replace tempdir with another directory path if you don't want to save to the temp dir.

% Write to text file
file = fullfile(tempdir,'Mymatrices.txt');
fid = fopen(file,'w+');
cleanup = onCleanup(@()fclose(fid)); 
fprintf(fid, '%s', txtCat);
clear cleanup
winopen(file) % Opens the text file, for Windows platforms

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Robert Bag 2021-5-14

Couldnt I just use dlmread and "skip" the rows with text in the reading?

Robert Bag 2021-5-14

And does "append" work with writematrix? Sry for all the questions but I am a beginner ;)

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Matrix insertion to a txt-file

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