MATLAB: I want to read text file with numeric data with line breaks every few thousand lines

breaks in datatextscan

Hello, I have a large text file in the format: '%s %s %s %d %f %f %f %f %f %f %f %f %s'.

Within the rows there are breaks in the data denoted by '—BREAK IN DATA —'.

I have determined the location of each break by using: row_idx = find(~cellfun('isempty',strfind(data,'— BREAK IN DATA —')));

How can I read all the rows of data between each break in the data? With textscan I can read up to the first break in the data and then it is cutoff.

Thank you!

Best Answer

If it is acceptable to read all of the data, then

datacell = textscan(fid, '%s %s %s %d %f %f %f %f %f %f %f %f %s', 'CommentStyle', '--- BREAK IN DATA ---');

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Hi, Liisa

Look at line

data = textscan(fid, '%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f');

Did you mean

data = textscan(row, '%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f');

And you can replace these lines

filepath=['..\matlab_testing\'];      
filena=['file' num2str(n) '.txt'];    
[filepath filena];
if exist([filepath filena])
fid=fopen([filepath filena],'rt');

with

fid = fopen(d(n).name,'rt');

Also at line

out = [];

should be placed outside the loop.

And about

data = textscan(row,'%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f');
out = [out; cell2mat(data)];

Can be replaced with

data = str2num(row);
out = [out; data];

So, the complete code is :

d = dir('*.txt');
out = [];
for n = 1 : numel(d)
    fid = fopen(d(n).name,'rt');    
    row = fgetl(fid);        
    %data = textscan(row,'%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f');
    data = str2num(row);
    %out = [out; cell2mat(data)];
    out = [out; data];
end

Now, just try to type out in command window and you'll get the result as 3 x 17 matrix.

I hope this helps.

MATLAB: Legend causes thousands of function calls

How are you calling legend? Are you just passing in the legend strings? If so then MATLAB needs to visit every object (such as lines) that are legend'able in order to determine whether they have custom legends, need to have a legend entry, or so on.

If that is what you are doing, then when you call legend(), pass in the explicit list of object handles that you are generating legends for, so that it does not need to visit the other objects.

Best Answer

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