Gold Member
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

Code:
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

Related MATLAB, Maple, Mathematica, LaTeX News on Phys.org
Office_Shredder
Staff Emeritus
Gold Member
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.

• dRic2 and Dale
Dale
Mentor
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
Gold Member
Line 17 should probably be value(j-pos)
Thank you so much

• Dale
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
Gold Member
Thanks @Arjan82, I'll look for the documentation about fscanf :)