MATLAB: Reading data from textfile

data import

I have one column of data with 600 rows and I want to know what does this statement do:

Column = data(1:11:end-10)

Best Answer

Create a 600x1 vector as follows

 data = (1:1:600)';

which is just a column vector with values set as 1 2 3 4 5 6 ….600.

Now run the command

 Column = data(1:11:end-10)

and observe the result. The data(1:11:end-10) extracts every eleventh row element (from data) starting at 1 and ending at the length of the array, given by end, less 10.

Related Solutions

MATLAB: Extract every tenth row from a long text file with 3 column

You forgot to attach the file, but basically I'm guessing you'd do:

data = importdata(filename);
% Non-loop way:
data10 = data(1:10:end, :);
% Loop way
[rows, columns] = size(data);
data10 = zeros(ceil(rows/10), columns);
thisRow = 1;
for row = 1 : 10 : rows
    data10(thisRow, :) = data(row, :);
    thisRow = thisRow + 1;
end

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: Extract every tenth row from a long text file with 3 column

MATLAB: Reading big textfile with textscan

Related Question