New Line in text file from Matlab

I want create multiple line and columns in text file from matlab to read measurement test data.

So far, I am able to do basic stuff. But any tips how can I proceed the above the task. Also the column should only contain 8 character. So there should be 10 column each column has 8 character in it. Character can be integer, strings

Answer 1

[Voss]

% random numbers for data to write to text file:
data = randn(20,10)*1e6;

% open the file for writing:
fid = fopen('test_output.txt','w');

% write each value as an 8-character-wide floating-point number, followed by
% a space; after every 10 such columns of values, write a newline (\n):
fprintf(fid,[repmat('%8f ',1,10) '\n'],data.');

% close the file:
fclose(fid);

% check that the resulting text file contains the same matrix as 'data',
% within the floating-point precision used:
data_from_file = readmatrix('test_output.txt');
difference = abs(data_from_file-data);
max(difference(:))

ans = 4.9942e-07

[Abhikaran Amitkumar Bhatia]

Thank you, I modify the code a bit. But I am stuck again.

Two problems I am facing with my current code which I have attached below.

1) No new line is created after 10 columns.

2) Is there a way to '+' sign after 9th column as I have commented in the code. So I need '+' sign in the beginning and another one at the end. Something like this.

% random numbers for data to write to text file:
str(1) = "TABLED1";
data1 = [str(1) 2001];
% data2 = values;

A = values1((1:4),(1:3));

% open the file for writing:
fid = fopen('test_output.txt','w');

% write each value as an 8-character-wide floating-point number, followed by
% a space; after every 10 such columns of values, write a newline (\n):
fprintf(fid,'%s %g\n',data1);
fprintf(fid,'%s',"+");

for i = 1:4
    for j = 1:3
            
        fprintf(fid,[repmat('%8.3f',1,10) '\n'],A(i,j).');
%         if repmat(A(1,>9))     %If the data exist from 9th column than it should have '+' sign in 10th column
%             fprintf(fid,'%s',"+");
%         end
    end
end


% close the file:
fclose(fid);

[Voss]

Can you attach a mat file containing your variable values1?

[Abhikaran Amitkumar Bhatia]

Here's the file

[Voss]

You can try something like this. I wasn't sure the order the elements of A should be printed to file, so check it.

S = load('values1.mat');
values1 = S.values;

% A = values1((1:4),(1:3));
A = values1((1:4),(1:3)).'

A = 3×4

0.0157 0.0156 0.0149 0.0147 -0.0031 -0.0018 -0.0035 -0.0033 -0.0030 -0.0033 -0.0037 -0.0023

fid = fopen('test_output.txt','w');

header = repmat('.',1,72);
header(1) = '$';
header(9:8:end) = '2':'9';
fprintf(fid,'%s\n',header);

str(1) = "TABLED1";
data1 = [str(1) 2001];

str_to_file = sprintf('%s ',data1);
fprintf(fid,sprintf('%%s%%%ds\n',73-numel(str_to_file)),str_to_file,'+');

count = 0;
fprintf(fid,'+');
fprintf(fid,'%7s',' ');
% for i = 1:4
%     for j = 1:3
for i = 1:3
    for j = 1:4
        fprintf(fid,'%-8.3f',A(i,j));
        count = count+1;
        if mod(count,8) == 0
            fprintf(fid,'+\n+');
            fprintf(fid,'%7s',' ');
            count = 0;
        end
    end
end
fprintf(fid,'ENDT');

% close the file:
fclose(fid);


% verifying the contents of the file:
fid = fopen('test_output.txt');
disp(char(fread(fid).'));

$.......2.......3.......4.......5.......6.......7.......8.......9.......
TABLED1 2001                                                            +
+       0.016   0.016   0.015   0.015   -0.003  -0.002  -0.004  -0.003  +
+       -0.003  -0.003  -0.004  -0.002  ENDT

fclose(fid);

[Abhikaran Amitkumar Bhatia]

Yes, this helps a lot. Thank You.

[Abhikaran Amitkumar Bhatia]

Hey,

So am used 'rem' instead of 'mod' and I still get the same result. How is mod different form rem?

Also for the if loop, this is what I have understood so far. The loop prints + sign after 7 character sets and then it creates new line again ending with an +, when the mod is 0. So when the count is 2,4,8 mod is zero.But in that case it would also print + sign in 2,4 and8, which is not the case when I run the file.Can you explain me that loop?

[Voss]

mod is different from rem for negative arguments - not a factor here.

mod(x,8) == 0 means x is a multiple of 8, not a multiple of 2. mod(x,2) == 0 would mean x is a multiple of 2.

Since the code is resetting count to 0 in that case, I could've just as easily done if count == 8 rather than if mod(count,8) == 0

fprintf(fid,'+\n+'); prints a + then starts a new line and then prints another + at the beginning of the new line. (Then fprintf(fid,'%7s',' '); prints seven spaces immediately after that first + of the line.)

So you've basically understood the loop already: it is printing each number, and when it has printed 8 numbers, end the line with a + and start the next line with a + and seven spaces, then continue printing numbers.

[Abhikaran Amitkumar Bhatia]

Okay, I understand. Thank you