How to select two columns of data based on flag present in 3rd column from a text file using Matlab

Hi All,

I want to pull out first and second column only if my flag is 1 in 3rd column and skip if it is zero.

My file contents is type

   10  20  0
   5   11  1
   6   7   1
   20  9   0
   100 3   1
   12  5   1
   .......

I have tried like

    dd=fopen('extract.txt');
    mm=fopen('output.txt','w');
  for i=1:207
      if dd(i,3)==0
          disp('skip');
      else dd(i,3)=1

      fprintf(mm,'%d\t%d\n',dd(i,3));
      end   
     end

It is showing error. How can I achieve this.

Thanks In Advance

Answer 1

[Walter Roberson]

    dd = fopen('extract.txt');
    mm = fopen('output.txt','w');
    for i=1:207
      if dd(i,3) == 0
          fprintf('skip 0 at i = %d\n', i);
      elseif dd(i,3) == 1
        fprintf('found 1 at i = %d, recording line\n', i);
        fprintf(mm,' %d\t%d\n',dd(i,1), dd(i,2));
      else
        fprintf('found unexpected value %g at i = %d, skipping it\n', dd(i,3), i);
      end   
    end
    fclose(mm)

But if you do not need those 'skip' and so on messages, then you can replace all of it with

    dd = fopen('extract.txt');
    selected = dd(dd(:,3) == 1, 1:2);

    mm = fopen('output.txt','w');
    fprintf(mm,' %d\t%d\n', selected .');   %transpose is important
    fclose(mm)

[POKA]

Thanks for your suggestions. I solved it through other way . I will check your one also .If you remember yesterday's problem , I have pulled Raim and Gga line to different file and filter them out using 5(flag). I have same number of Raim and Gga lines . So it is solved now . Thanks

Answer 2

[Image Analyst]

Why not simply read the whole thing in and extract the rows you need?

data = csvread(filename); % Read in all the data.  Can also use importdata().
rowsToExtract = data(:, 3) == 1; % Find rows with 1 in column 3
% Extract columns 1 and 2 but only those rows.
data = data(rowsToExtract, 1:2);

[POKA]

I did like this

 X=load('file.txt')
 Fikterdta=X(X(:,end)==1,:)
 fprintf(mm,'%d....,fikterdata)

It worked

[POKA]

It is because this matrix is one of the step in my coding process which is text file .I will check your one also .

[POKA]

Just asking ,is it possible to give stylish apperaness of output MATLAB figure . something we see in power point presentation or sometimes our desktop display. Can we manipulate output MATLAB figure to get impressive one instead of general pop up . wanted to learn . Thanks

[Image Analyst]

You can use sprintf() and fprintf() to make a nicely aligned table if you use a non-proportional font, like Courier. You might also want to use a spreadsheet-like control called a "uitable" on your GUI.