MATLAB: Remove the character ” * ” on a txt file to create a “clean” matrix

remove characterstxt file

Hi guys.

Let me start wishing that everyone is ok due to COVID pandemic.

I have a .txt file with an excess of " * " carachters. What i want to do is to get rid oh those and create an 3 column matrix containing only the numbers. At this moment i have this:

    clc;
    clear all;
    close all;
    [name,path]=uigetfile('.txt','Select File To Open');
    file=[path,name];
    A=textread(file,'%f %f %f',1,'headerlines',3,'delimiter','*');

and it gives me the following error:

    Error using dataread
       Number of outputs must match the number of unskipped input fields.
    Error in textread (line 171)
    [varargout{1:nlhs}]=dataread('file',varargin{:}); %#ok<REMFF1>
    Error in Untitled (line 9)
    A=textread(file,'%f %f %f',1,'headerlines',3,'delimiter','*','whitespace','');

I don't know how to fix so if you could help me i'll appreciated. I've attached the txt file.

Thanks in advance a please, stay safe.

Best Answer

S = fileread('dump.txt');
S(S == '*') = '';
A = cell2mat( textscan(S, '%f %f %f', 'headerlines', 3));

Related Solutions

MATLAB: Load a txt file:

You could use the function textscan, which lets you select the headerlines to ignore (so you don't need to delete any lines by hand), and also define the number of rows that should be read into MATLAB.

EDIT to match newly uploaded textfile.

This code reads that text file, including the header, the matrix, and the trailing data. It also adjusts automatically to the number of columns.

fid = fopen('myexamplefile.txt','rt');
line1 = fgetl(fid);
hdr = regexp(fgetl(fid),'\S+','match');
fmt = repmat('%f',1,numel(hdr));
C = textscan(fid,fmt);
D = textscan(fid,'%s%s%s%s',1,'HeaderLines',1);
fgetl(fid);
E = textscan(fid,'%s%f%f%f%f',1,'HeaderLines',1);
fclose(fid);

MATLAB: Reading big textfile with textscan

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:

Best Answer

Related Solutions

MATLAB: Load a txt file:

MATLAB: Reading big textfile with textscan

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