How Do You Correctly Parse and Convert Strings to Numbers in Octave?

[dRic2]

Hi, I used to use MATLAB for this kind of thing, but now my pc broke and I need to run some scripts. I have a .txt file structured like this

10 -2.34454
12 -2.34566
14 -2.34677
... ...

and I want to store the data in two variables: the first is the "counting" (10, 12, ...) and the second is the value (-2.34454, ...). So I wrote the following script, but I run in the following problem

function [out1, out2] = read(fid)
    i = 1;

    while true
      currentline = fgetl(fid);
      if (currentline == -1)
        break;
      end
 
      pos = find(currentline == ' ');
 
      for j=1:pos
        count(j) = currentline(j);
      end

      for j=(pos+1):(length(currentline))
        value(j) = currentline(j);
      end
   
      count_num(i) = str2num(count);   % <--------- THIS WORKS
      value_num(i) = str2double(value); % <-------- THIS DOES NOT WORK !
      i++;
    end
 
    out1 = count_num;
    out2 = value_num;
end

The problem is that while I get my nice vector count_num = [10 12 14 ...], the other vector is [NaN, NaN, ...]. I also tried to add disp(value) to see if the string is acquired correctly and it is! The problem is the conversion! str2num also doesn't work.

Any help would be highly appreciated.

Ric

 

[Office_Shredder]

The first thing I would do is check if your string starts with a space and you need to just exclude it. The second thing is if it's interpreting the - as a minus sign correctly - if you omit that character does it work? Lastly I would try to drop the last character, it might be reading a weird ending character it doesn't know what to do with.

 

[Dale]

Line 17 should probably be value(j-pos) or something similar.

In general, when you have a standard routine failing you need to look at the inputs.

 

[dRic2]

Line 17 should probably be value(j-pos)

Thank you so much

 

[Arjan82]

This script can be massively simplified:

function [out1, out2] = read(fileName)

    fid = fopen(fileName)
    d = fscanf(fid,'%f', [2 inf])';
    out1 = d(:,1);
    out2 = d(:,2);
    fclose(fid);end

 

[dRic2]

Thanks @Arjan82, I'll look for the documentation about fscanf :)