Read a Special Text File

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AEW
AEW on 22 Apr 2022
Commented: AEW on 23 Apr 2022
I was wondering if there is a quick way to read the following text file sample where the first data line starts with a bracket. I would like to avoid the hassle of manually removing the bracket from every file I obtain. I use the following command for now after I remove the bracket.
Thanks.
data = textscan(Fopen, '%d %f %d %d %d;', 'HeaderLines',2)
file.txt
  1 Comment
Stephen23
Stephen23 on 23 Apr 2022
A simple and very efficient approach would be to simply define the square bracket as whitespace, which you can do using TEXTSCAN's WHITESPACE option. Another good approach would be to use a fixed-width import via READTABLE.
Using STR2NUM is not very efficient.

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Accepted Answer

Stephen23
Stephen23 on 23 Apr 2022
Edited: Stephen23 on 23 Apr 2022
Here are two much more efficient approaches.
The first is exactly like you are doing now, just adding the WHITESPACE option to efficiently ignore the square bracket:
fnm = 'textfile.txt';
fmt = '%d%f%d%d%d;';
opt = {'HeaderLines',2, 'Whitespace',' \t['};
fid = fopen(fnm,'rt');
data = textscan(fid, fmt, opt{:})
data = 1×5 cell array
{11130×1 int32} {11130×1 double} {11130×1 int32} {11130×1 int32} {11130×1 int32}
fclose(fid);
The second is to import the file as table, which has headers and may be more convenient to access:
opt = detectImportOptions(fnm, 'FileType','fixedwidth', ...
'VariableWidths',[6,9,16,16,16], 'VariableNamesLine',1, ...
'VariableNamingRule','preserve', 'Range',3, 'Whitespace',' [', ...
'ExtraColumnsRule','ignore');
tbl = readtable(fnm,opt)
tbl = 11130×5 table
Sample Time Commanded Pos Encoder 1 Pos Encoder 2 Pos ______ _____ _____________ _____________ _____________ 0 0 0 0 0 1 0.001 0 0 0 2 0.002 0 0 0 3 0.003 0 1 0 4 0.004 0 4 0 5 0.004 0 7 0 6 0.005 0 14 0 7 0.006 0 20 0 8 0.007 0 27 0 9 0.008 0 37 0 10 0.009 0 47 0 11 0.01 0 57 1 12 0.011 0 66 3 13 0.012 0 76 4 14 0.012 0 87 6 15 0.013 0 98 7

More Answers (2)

Voss
Voss on 22 Apr 2022
Edited: Voss on 22 Apr 2022
% read file into character vector data
data = fileread('textfile.txt');
% remove the first two lines
idx = find(data == newline(),2);
data(1:idx(end)) = [];
% convert to numeric
M = str2num(data);
% show some results
format long
disp(M(1:10,:));
0 0 0 0 0 1.000000000000000 0.001000000000000 0 0 0 2.000000000000000 0.002000000000000 0 0 0 3.000000000000000 0.003000000000000 0 1.000000000000000 0 4.000000000000000 0.004000000000000 0 4.000000000000000 0 5.000000000000000 0.004000000000000 0 7.000000000000000 0 6.000000000000000 0.005000000000000 0 14.000000000000000 0 7.000000000000000 0.006000000000000 0 20.000000000000000 0 8.000000000000000 0.007000000000000 0 27.000000000000000 0 9.000000000000000 0.008000000000000 0 37.000000000000000 0
disp(M(end-9:end,:));
1.0e+05 * 0.111200000000000 0.000098460000000 0 1.003280000000000 0.222970000000000 0.111210000000000 0.000098470000000 0 1.002280000000000 0.222750000000000 0.111220000000000 0.000098480000000 0 1.001270000000000 0.222530000000000 0.111230000000000 0.000098480000000 0 1.000280000000000 0.222310000000000 0.111240000000000 0.000098490000000 0 0.999280000000000 0.222090000000000 0.111250000000000 0.000098500000000 0 0.998290000000000 0.221870000000000 0.111260000000000 0.000098510000000 0 0.997310000000000 0.221640000000000 0.111270000000000 0.000098520000000 0 0.996330000000000 0.221420000000000 0.111280000000000 0.000098530000000 0 0.995360000000000 0.221190000000000 0.111290000000000 0.000098540000000 0 0.994390000000000 0.220970000000000
  2 Comments
Voss
Voss on 23 Apr 2022
You're welcome!

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David Hill
David Hill on 22 Apr 2022
r=readmatrix('file.txt');%see if this will work
  3 Comments
AEW
AEW on 22 Apr 2022
Please find it attached.
Thanks.

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