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How to read data from a file into cell array keeping indents undisturbed

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Shankar Santhosh
Shankar Santhosh on 27 Sep 2020
Commented: Shankar Santhosh on 28 Sep 2020
I am trying to read a data from a file, modify it and write to a same file which I did using,
fid = fopen('file.ext','r');
fclose(fid);
lines = textscan(fid,'%s','Delimiter','\n');
...
fid = fopen('file.ext','w');
for row = 1:length(lines{1})
fprintf(fid,'%s\n',lines{1}{row});
end
fclose(fid);
But I could not reproduce the indents which were in the original file. So any suggestions to achieve this and make the above process easier?
Note: the file extension is not .txt but similar to text format. The data which I try to read has html tag elements and attributes.
I would also like to know whether there is any way to directly modify a file without reading it?
Thanks in advance!

  2 Comments

Jan
Jan on 27 Sep 2020
If you close the file by fclose before running textscan, the code should fail with an error message.
Shankar Santhosh
Shankar Santhosh on 28 Sep 2020
You are right! I just misplaced the lines in this query. But I had it right in my code.

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Accepted Answer

Jan
Jan on 27 Sep 2020
Edited: Jan on 27 Sep 2020
% Import file:
Str = fileread('file.ext');
% Remove trailing line break to avoid appending an additional empty line:
if ~isempty(Str) && Str(numel(Str)) == char(10)
Str(numel(Str)) = [];
end
% Split lines:
% lines = strsplit(Str, char(10));
% Faster but uglier (this is what happens inside STRSPLIT):
lines = regexp(Str, ['(?:', char(10), ')+'], 'split');
...
% Write output:
fid = fopen('file.ext', 'w');
fprintf(fid, '%s\n', lines{:});
fclose(fid);

  1 Comment

Shankar Santhosh
Shankar Santhosh on 28 Sep 2020
This is exactly what I needed !
Working fine with my scenario. Thanks a lot.
You are great ../\..

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More Answers (1)

Rik
Rik on 27 Sep 2020
You can get my readfile function from the FEX or through the AddOn-manager (R2017a or later).
It will read a file to a cell array, one cell element per line, and it will preserve all leading and trailing spaces.
One of the advantages of a cell array is that you can trivially write out the modified file: fprintf(fid,'%s\n',txt{:}).

  3 Comments

Shankar Santhosh
Shankar Santhosh on 28 Sep 2020
This is great, but I am in a situation where I need to make this change that should be compatible in all MATLAB releases starting from R2012b. Anyway thanks for the info.
Rik
Rik on 28 Sep 2020
This is compatible all the way back to Matlab 6.5, and it works on GNU Octave.

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