Reading big textfile with textscan
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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.
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Stephen23
2015-7-20
编辑:Stephen23
2015-7-20
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:
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