How do I overwrite part of a .tsv file?

3 次查看（过去 30 天）
Josh Walker
Josh Walker 2023-2-21
评论： Josh Walker 2023-2-22
I need to replace some old data in a .tsv file with new data. I need to keep the first 13 rows of the original file and overwrite the following 40000 rows with 40000 rows of the new data. I have used the following code for this:
dlmwrite('MyFile.tsv',M,'precision','%.6f','delimiter','\t','roffset',13);
, which appends my new data on the original file. However, I cannot find a way of overwriting only part of the original file...'-append' does not seem to work/help.
Any help would be appreciated.

请先登录，再回答此问题。

回答（2 个）

Image Analyst
Image Analyst 2023-2-21
Try this
data = dlmread(filename); % Get old data.
% Now change ONLY rows 14 and lower.
% Now write back the entire matrix.
dlmwrite('MyFile.tsv', M, 'precision', '%.6f', 'delimiter', '\t');
  3 个评论
显示 1更早的评论
Image Analyst
Image Analyst 2023-2-21
Personally I'd just use fprintf() to manually write it out line by line.

请先登录，再进行评论。

Walter Roberson
Walter Roberson 2023-2-21
dlmwrite always overwrites all of the text file unless -append is used. There is no way to get dlmwrite to overwrite part of a text file.
There is also no way to get writetable or writematrix or writecell to overwrite part of a text file.
The fundamental technical implementation of text files, in all operating systems since Vax VMS RMS, has only permitted overwriting with exactly the same number of characters. (There are also operating system calls to truncate a file, but MATLAB does not provide access to those)
  2 个评论
Walter Roberson
Walter Roberson 2023-2-21
You can use readcell() and writecell to overwrite the entire file while keeping the identity of the initial lines as text, but there is the danger that the headers might get extra tabs put on the end so that the number of columns matches.
Josh Walker
Josh Walker 2023-2-22
Thanks! I had tried this to some extent and had a similar problem of getting extra tabs.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Text Files 的更多信息

标签

产品


版本

R2022a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by