How to select rows with a particular value form one text file and write desired rows in new file?

Let's say I have the following data

3   43.45  0.5
4   23.21  0.4
5   32.84  0.3
6   67.02  0.4
2   13.00  0.2
3   23.32  0.1

How would I only select the rows in which the 3rd column elements are less than 0.4 and write them into a new file?

Then in this new file I would only have row 3,5 and 6 in this new file.

Answer 1

[KALYAN ACHARJYA]

k=load('test1.txt');
idx=k(:,3)<0.4;
k(idx,:)
%Next save the file as new name, hope you can do that.
%Still if you need help, comment below

ans =

    5.0000   32.8400    0.3000
    2.0000   13.0000    0.2000
    3.0000   23.3200    0.1000
    

Answer 2

[Bob Thompson]

I'm assuming the file only has numeric data.

data = dlmread('yourfilename.txt');
datan = data(data(:,3)<0.4,:);
dlmwrite('yournewfilename.txt',datan,'delimiter',' ');

You can change precision, by adding 'precision' and some form of precision (similar to fprintf), to the dlmwrite command. This will allow you to have extra zeroes, or spaces or things of that nature.