Reading last lines in a text file

Hey everyone!

I have a quick question. I want to read the last 100 data from a .txt file. The .txt will update now and then, but I need the last 100.

The file looks like this :

22 40866

18 40867

17 40868

9 40869

81 40868

81 40870

I'm using this code for reading :

fid = fopen('HCl.txt');
A = textscan(fid, '%s %s', 'delimiter', '\t');
fclose(fid);

I want to keep textscan because it reads in a way that I get arrays. A{1,1} and A{1,2}

A{1,1} = [22 18 17 9 81 81]

A{1,2} = [40866 40867 40868 40869 40868 40870 ]

So by reading(let's say) the last 2, I should get :

A{1,1} = [81 81]

A{1,2} = [40868 40870 ]

I found something but it applies only to fscanf which doesn't give out in arrays. It goes something like R = A(end,2:end)

Thank you in advance!

Answer 1

[Fangjun Jiang]

Your data are numerical so I think it's better to read them as numerical data.

fid = fopen('HCl.txt','rt');
A = textscan(fid, '%f %f', 'delimiter', '\t','collectoutput',true);
A=A{1};
fclose(fid);

It will give you nx2 matrix where n is the number of lines. Then you can do the following.

n=size(A,1);
if n>100
NewA=A(end-99:end,:);
else
NewA=A;
end

[Slobodan Djordjevi?]

Thanks!

It says n=1, and I have 228 lines of data.

I see where you are getting at!

[Slobodan Djordjevi?]

Any new ideas? I tried changing some things but still nothing...

[Fangjun Jiang]

Sorry, A is a cell array as it is now in the code. Run A=A{1} or A=cell2mat(A) after the textscan() reading. You'll get a nx2 matrix.

[Slobodan Djordjevi?]

Fangjun Jiang, you are my angel! :)

Thanks man!