Reading .txt files and replace numbers from one file to another

Hello, I have a problem with a code.

First of all I have two .txt files, file1.txt and file2.txt.

File1 has 2 columns with 3 lines, and File2 has 5 columns with 20 lines. I would like to read this files and after that I would like to take the two numbers of the first line of File1.txt and replace these two numbers to the column 3 and column 4 of the first line of the File2.txt.

I try to create a loop, but I can not understand how to create this code.

Could anyone help me?

[Geoff Hayes]

Ivan - please post the code that you have written so that we can help you understand what isn't working with the code.

[Ivan Mich]

my code is incomplete because I don't understand how I can get specific data from the file so I'm confused.

clc
clear

file1=fileread('file1.txt')
file2=fileread('file2.txt')

filenameB = 'file2.txt';
outfilenameB = 'file2.txt';
LineToChange1 = 5;
NewContent1 = ' .....';
S = fileread(filenameB);
SS = regexp(S, '\r?\n', 'split');
SS{LineToChange1} = NewContent1;
fid = fopen(outfilenameB, 'w');
fprintf(fid, '%s\n', SS{:});
fclose(fid);

the point is that I would like to replace the values of 3rd nad 4th column of the first line of file2.txt (521 625 in file2.txt) with the values of the first line in file1.txt (6.4 30 in file1.txt). I think i should use a loop with for but i can not compose my code. I sent you these files for your facilitation.

Thank you in advance

Answer 1

[Geoff Hayes]

Ivan - try using importdata to read your text files, perhaps something like

file1Data = importdata('file1.txt', ' ', 1); % skip the header row
file2Data = importdata('file2.txt');

Now you have two matrices and so you should be able to access the appropriate rows of either to do whatever changes are necessary. You can then write out the results back to file with writematrix or equivalent.

[Ivan Mich]

OK, but I don't understand what commands should i use in order to replace the data I want, from one file to another

[Geoff Hayes]

Ivan - if the import works correctly, then file1Data will be a 3x2 array and file2Data will be a 20x5 array. If you want to replace the 3rd and 4th columns of the first row of file2Data with the first row of file1Data then you would do

file2Data(1,3:4) = file1Data(1,:);

[Ivan Mich]

ok, and if I want to replace the 3rd and 4th columns of every row of file2 with the file1 and after finishing replacing all the rows with the first row of file1, after that I would like to do the sam ereplacing with the 2nd row etc.. how could I make it?

[Geoff Hayes]

So does every row of file2 get replaced with the first two elements of the first row of file1? Or does the second row of file2 get replaced with elements of the second row of file1? Please clarify.

[Ivan Mich]

Well,I have two .txt files. The first , let's call it File1.txt, has 2 columns and 3 lines. The second let's call it File2, has 10 lines. I would like to replace line number 9 in file2 by importing the first line from the file1.txt. After that I would like to replace line number 9 in file2 by importing the second line from the file1.txt. And last I would like to replace line number 9 in file2 by importing the third line from the file1.txt.

I believe that I should make cnanges in "NewContent", but I am sure that I have to create a loop. My problem is that I do not know the way to make it.

[Ivan Mich]

i have tried this but it is no working:

clc
clear
file1=importdata('file1.txt');
X=file1.data(:,1);
R=file1.data(:,2);
file2='_tst_C_.params'
ex=readfile(file2)'
filename=file2
outfilename2 = 'new.params';
LineToChange = 9;
NewContent = X R;
S = fileread(filename);
SS = regexp(S, '\r?\n', 'split');
SS{LineToChange} = NewContent;
fid = fopen(outfilename2, 'w');
fprintf(fid, '%s\n', SS{:});
fclose(fid);

[Geoff Hayes]

why are you using three types of file reading function?

file1=importdata('file1.txt');  % <---- importdata
X=file1.data(:,1);
R=file1.data(:,2);
file2='_tst_C_.params'
ex=readfile(file2)'             % <---- readfile - does this exit??
filename=file2
outfilename2 = 'new.params';
LineToChange = 9;
NewContent = X R;
S = fileread(filename);         % <---- fileread

I don't understand what you mean by

I would like to replace line number 9 in file2 by importing the first line from the file1.txt. After that I would like to replace line number 9 in file2 by importing the second line from the file1.txt. And last I would like to replace line number 9 in file2 by importing the third line from the file1.txt.

Why do you want to replace line 9 (of file 2) with line 1 (of file 1), then line 2 (of file 1) and then with line 3 (of file 1)? Do you want to write to a new file each time you update this line? Which columns of line 9 do you want to change, 3 and 4 still, or has that changed?

file1Data = importdata('file1.txt', ' ', 1); % skip the header row
file2Data = importdata('file2.txt');
for k = 1:size(file1Data,1)
    file2Data(9,3:4) = file1Data(k,1:2);
    % do something??
end

[Ivan Mich]

Yes, I would like to to write to a new file each time you update this line. Yes I want to change line 9 with the data I mentioned...

[Ivan Mich]

ok , one last question. Supposing that File2.txt has no columns but has only string characters, how could I replace a line of file2 with a line of File1.txt?

[Geoff Hayes]

Is the line of File1.txt a string? Are the strings in each line of File2.txt the same length? Please illustrate with an example of what you want to do...

[Ivan Mich]

I am uploading the two files in order to understand what I want to do. in these files, I would like to replace line 3 from File2 once with the first line of File1, once with the second line of file1 and once with the third line of File1.

I have to mention that i use readfile('File2.txt') in order to read this file.