How to delete the first 2 rows (Headers) of a txt file ?

Hello,

How to delete the first two rows , which are Headers , in a .txt file? I use these command to read it

file=regexp(fileread('data.txt'), '\r?\n', 'split') .';

Answer 1

[dpb]

Well, once you've got the right content in memory, then just rewrite the file. But, specifically on that has some bearing on the content for easy ways.

But, if that is the only thing you care to do, then the simplest irrespective of what the file content is, is probably

fidi=fopen('oldfile.txt','r');
fido=fopen('newfile.txt','w');
headerlines=2;
for i=1:headerlines,fgetl(fidi);end       % skip the desired number
buf=fread(fidi,'*char');                  % suck up the rest as image
fwrite(fido,buf)                          % and spit it out verbatim
fclose('all')                             % done
%delete('oldfile.txt')                    % optionally remove the original keeping new

%movefile('newfile.txt','oldfile.txt')    % optionally rename new to old (only new left as oldfile name)

[Ivan Mich]

ok thank you. I have tried to use your solution to a .out file, and not a .txt file as I mentiones, but I realised that it is no use.

Command window show me the message:

Error using fwrite

Not enough input arguments.

Do you know why?

[dpb]

Forgot the output to write...

fwrite(fido,buf)

[dpb]

Of course, one can just use

...
fwrite(fido,fread(fidi,'*char')); % suck up the rest as image and spit it out verbatim
...

Answer 2

[Geoff Hayes]

Ivan - perhaps try using importdata and indicate the number of header lines that should be ignored when reading in the file.

[Ivan Mich]

ok thank you, but the point is that I do not want only to read the file. I would like also to create a new .txt file with the content of "data.txt" and without headers. How can I use fopen to do this?

[Geoff Hayes]

Ivan - do you have to use fopen or can you use writematrix on your input? Assuming that your text file contains numeric data only then

filename = 'data.txt';
delimeter = ',';           % <---- assumes comma separated columns
A = importdata(filename, delimeter, 2);
writematrix(A, filename, 'Delimiter', delimeter);

The above assumes comma separated columns. If this isn't the case, then you can change it to whatever character separates the columns. If there is no delimeter, then this method probably won't work.

Answer 3

[dpb]

Or, readtable.

But, starting with the above simply

file=regexp(fileread('data.txt'), '\r?\n', 'split') .';
file=file(3:end);

Not knowing content of the file, or the next steps, hard to know what's the best approach but one would think unless it is just a list of string data in one column that it would be far better to interpret the file on input than just read characters.

[Ivan Mich]

dpb , ok thank you, nut the point is that I do not want only to read the file. I would like also to create a new .txt file with the content of "data.txt" and without headers. How can I use fopen to do this?

[dpb]

Well, once you've got the right content in memory, then just rewrite the file.

If that is the only thing you care to do, then the simplest irrespective of what the file content is, is probably

fidi=fopen('oldfile.txt','r');
fido=fopen('newfile.txt','w');
headerlines=2;
for i=1:headerlines,fgetl(fidi);end       % skip the desired number
buf=fread(fidi,'*char');
fwrite(fido)
fclose(all)