Reading big textfile with textscan

Hi,

I want to read a big textfile (~5MB) with textscan. The first 10 rows contain some informations which I don't need. Then 1024 rows with 1280 numbers per row follow. The numbers are separated by a comma. I found almost the right code except that each comma induces a new row instead separating the numbers. To use this code I have to delete the first 10 rows in my file.

fid = fopen('textfile.txt')
Out  = textscan(fid,'%f','delimiter',sprintf(','));
fclose(fid)

How should I manipulate the code so that I get a 1024x1280 array? I tried

sprintf('\n')

instead but that just gives me the first number and then stops.

Answer 1

[Stephen23]

Solution One

You do not need to delete the first ten rows from the file, because textscan has an option to ignore header lines, so you can use this instead:

Out = textscan(....,'HeaderLines',10);

To read 1280 columns of data you need to define this in the format string, so the final code could be something like this:

fmt = repmat('%f',1,1280);
fid = fopen('textfile.txt','rt')
out = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',10);
fclose(fid);

Solution Two

If the data in the matrix is all numeric (note the header lines do not need to be) then you could use the much simpler dlmread instead, something a bit like this:

out = dlmread('textfile.txt',',',10,0);

Examples

% textscan
fmt = repmat('%f',1,5);
fid = fopen('temp.txt','rt');
out_txt = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',3);
fclose(fid);
out_txt = cell2mat(out_txt)
% dlmread
out_dlm = dlmread('temp.txt',',',3,0)

display this in the command window:

out_txt =
     0     1     2     3     4
     5     6     7     8     9
out_dlm =
     0     1     2     3     4
     5     6     7     8     9

The sample text file that I used is attached here:

[David Pfläging]

It works perfectly! Thank you very much!