How to trim a text file with start and end line numbers

Asked by Jaffrey Hudson Immanuel Jeyakumar on 25 Jun 2019

Latest activity Commented on by Jaffrey Hudson Immanuel Jeyakumar on 25 Jun 2019

Accepted Answer by Vismay Raj

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data.txt

Hello ,

I want to trim the data.txt file with the start and end line numbers,

for example,

start line number = 5

end line number =10

I want a new .txt file with the lines only between 5 and 10.

I have attached a model data.txt with this question. Can anyone help me ?

MATLAB R2015b

Regards,

Jaffrey Hudson

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Products

MATLAB

Release

R2015b

2 Answers

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Answer by Vismay Raj on 25 Jun 2019

Accepted Answer

read the file using

filetext = fileread('file.txt')

split the text on newline and store the array of lines in a new variable

newstr = splitlines(filetext)

use start:end in array to display required elements

s = 5
e = 10
newArr = newstr(s:e)

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Jaffrey Hudson Immanuel Jeyakumar on 25 Jun 2019

Yes. The newArr,

newArr =

[1x41 char] [1x41 char] [1x41 char] [1x41 char] [1x41 char] [1x41 char]

The values are stored correctly.

What is the command to write the newArr in a new text file ?

Vismay Raj on 25 Jun 2019

follow this link https://www.mathworks.com/help/matlab/ref/fprintf.html?searchHighlight=fprintf&s_tid=doc_srchtitle

Jaffrey Hudson Immanuel Jeyakumar on 25 Jun 2019

Thank you.

I wrote like this,

fileID = fopen('exp.txt','w');

%fprintf(fileID,'%6s %12s\n','x','exp(x)');

fprintf(fileID,'%s',newArr);

fclose(fileID);

Can you pease correct my script ?

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Answer by Pullak Barik on 25 Jun 2019

I use the code-generator from the import tool to only import the lines needed from the text file, and then copied the cropped content to a new file.

% Auto-generated by MATLAB
% Setup the Import Options
opts = delimitedTextImportOptions("NumVariables", 1);
start_line_no = 5; %Change this variable to specify the starting point
end_line_no = 10; %Change this variable to specify the ending point
% Specify range and delimiter
opts.DataLines = [start_line_no, end_line_no];
opts.Delimiter = "!";
% Specify column names and types
opts.VariableTypes = "string";
opts = setvaropts(opts, 1, "WhitespaceRule", "preserve");
opts = setvaropts(opts, 1, "EmptyFieldRule", "auto");
opts.ExtraColumnsRule = "ignore";
opts.EmptyLineRule = "read";
% Import the data
test = readtable("C:\Users\pullak\Documents\MATLAB\data.txt", opts);
%Change the path above to point to your data.txt
% Convert to output type
test = table2array(test);
% Clear temporary variables
clear opts
%% Auto-generated code ends here
path = 'crop_data.txt'; 
%This stores the cropped data in the directory of the code script file, change the path as per your will
fid = fopen(path, 'w');
fprintf(fid, '%s\n', test{:});
fclose(fid);

1 Comment

Jaffrey Hudson Immanuel Jeyakumar on 25 Jun 2019

Thank you for the alternative solution too.

Products

MATLAB

Release

R2015b

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