parse text file in MATLAB

Question

How can I parse file in MATLAB? The data in the text has this format:

p
15.01245  20.478
12.589  58.256
n
16.589  87.268
52.367  46.256
2.589  58.02

I want to store each data in separate array (i.e; store data under letter p in array 1, and data under letter n in array 2).

any help?

Molly · Answer 1 · 2013-04-01T20:41:38.110

4

You can do this by using fgets to read in the file line by line and checking for lines containing p and n.

fid = fopen('pn.txt'); % open the file
i2 = 1;
data = {};
while ~feof(fid) % loop over the following until the end of the file is reached.
      line = fgets(fid); % read in one line
      if strfind(line,'p') % if that line contains 'p', set the first index to 1
          i1 = 1;
      elseif strfind(line,'n') % if that line contains 'n' set the first index to 2
          i1 = 2;
      else
          data{i1,i2} =  str2num(line); % otherwise, it the line contains numbers, add them to a cell array.
          i2 = i2 + 1;
      end
end
fclose(fid);

%convert the cell array into two matrices.
p = cell2mat(data(1,:));
p = reshape(p,[numel(p)/2,2])
n = cell2mat(data(2,:));
n = reshape(n,[numel(n)/2,2])

edited Apr 01 '13 at 20:41

answered Apr 01 '13 at 19:59

Molly

13,240
4
44
45

Thanks, but the last two lines gave me this error :Error using cell2mat (line 46) All contents of the input cell array must be of the same data type. – userInThisWorld Apr 01 '13 at 20:15
Do you get that error using the example file you included above? – Molly Apr 01 '13 at 20:18
I see you've got a working answer, but I updated my answer as well. – Molly Apr 01 '13 at 20:42

score 4 · Accepted Answer · answered Apr 01 '13 at 20:19

4

Here is another solution:

fstring = fileread('test.txt'); % read the file as one string
fblocks = regexp(fstring,'[A-Za-z]','split'); % uses any single character as a separator
fblocks(1) = []; % removes anything before the first character
out = cell(size(fblocks));
for k = 1:numel(fblocks)
    out{k} = textscan(fblocks{k},'%f %f','delimiter',' ','MultipleDelimsAsOne', 1);
    out{k} = horzcat(out{k}{:});
end

answered Apr 01 '13 at 20:19

yuk

19,098
13
68
99

thanks , but how i can read data? – userInThisWorld Apr 01 '13 at 20:22
`out{1}` is the first array, `out{2}` - the 2nd, etc. – yuk Apr 01 '13 at 20:23

parse text file in MATLAB

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