Hello good... I would like to know how I can skip the comments header of a text file with data for a graph please :c

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Lya Lopez 2022-4-14

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回答： Image Analyst 2023-9-11

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Benjamin Thompson 2022-4-14

Can you use the data import tool? Right click on the file in the MATLAB file listing and select "Import Data". Otherwise please post a sample of your file for the Community to see.

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Answer 1

Siraj 2023-9-11

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Hi! It is my understanding that you want to read a text file while excluding any header comments present in the file.

Method - 1

One approach to exclude header comments when reading a text file is by utilizing the "fgetl" function to skip a specific number of lines, assuming you already know the number of header lines to skip. Below is an example for better clarity:

The contents of the file "file1.txt" used in the example below are as follows:

Comment 1
Comment 2
Comment 3
1 2 1
1 2 3
2 3 4
4 4 6

Here is an example code snippet.

% Specify the file path and name
file = 'file1.txt';
% Open the file for reading
fid = fopen(file, 'r');
% Specify the number of header lines to skip
numHeaderLines = 3;
% Skip the header lines
for i = 1:numHeaderLines
    fgetl(fid);
end
% Read the data using textscan
data = textscan(fid, '%f %f %f');
% Close the file
fclose(fid);

Method - 2

Another approach is instead of manually skipping a fixed number of header lines, utilize the comment style option in the “textscan” function to skip lines starting with a specific character, such as '#'. This approach allows you to dynamically skip any number of header or comment lines present in the file. Below is an example for better clarity:

The contents of the file "file2.txt" used in the example below are as follows.

#Comment 1
#Comment 2
#Comment 3
1 2 1
1 2 3
2 3 4
4 4 6

Here is an example code snippet

% Open the file for reading
file = 'file2.txt';
fid = fopen(file, 'r');
% Read the data using textscan and skip lines starting with '#'
data = textscan(fid, '%f %f %f', 'Delimiter', '\t', 'CommentStyle', '#');
% Close the file
fclose(fid);