Import and modify " .txt" files

Question

0 个投票

Hi

I have some ".txt" files with this structure :

useless
useless
useless
...
data
data
...
useless
useless
useless
data
...

And I would like to have a .txt file like this :

data
data
data
...

I just know that each first line of data section begins with '1' but the length of the headerline (useless) is not fixed ! So I would like to iterate until lines begins with '1' and then keep the data.

How would you do that the easiest way ?

Thanks a lot

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johnmay 2015-11-26

Here is a sample file. As you can see 'X-Axis Size' gives me the number of measurement points (10) and I still have this value with some code (strfind...)

johnmay 2015-11-26

Sorry, here it is... And file2 is what I want

Many thanks

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Answer 1

Thorsten 2015-11-26

在 MATLAB Online 中打开

0 个投票

Copy those lines that have four numbers:

fid = fopen('file.txt', 'r');
fid2 = fopen('file2.txt', 'w');
line = fgets(fid);
while line ~= -1
  [~, count] = sscanf(line, '%f');
  if count == 4
    fprintf(fid2, '%s', line);
  end
  line = fgets(fid);
end
fclose(fid)
fclose(fid2)

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Thorsten 2015-11-26

You mean reading and write to the same file? No, I don't think so.

johnmay 2015-11-26

Last question : when using 'fprintf' is there a way to write only the 'x' first columns of my line? and not the whole line So that the final file has a constant number of columns and could be opened easily ?

Many thanks

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Answer 2

johnmay 2015-11-26

0 个投票

Last question : when using 'fprintf' is there a way to write only the 'n' first columns of my line? and not the whole line. So that the final file has a constant number of columns (n) and could be opened easily ?

Many thanks

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Walter Roberson 2015-11-27

在 MATLAB Online 中打开

Before the loop:

   n = 2;    %whatever is appropriate
   fmt = repmat('%f ', 1, n);
   fmt(end:end+1) = '\n';    %newline, unrelated to the variable 'n'

In the loop:

[data, count] = sscanf(line, '%f');
if count >= n
  fprintf(fid2, fmt, data(1:n));
end

johnmay 2015-12-1

Thanks a lot. I just tried but it doesn't work, it seems like it concatenates data in a single line.. Anyway many thanks

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Import and modify " .txt" files

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