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

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Marisabel Gonzalez 2018-11-29

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编辑： KALYAN ACHARJYA 2018-11-29

Let's say I have the following data

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.

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Answer 1

KALYAN ACHARJYA 2018-11-29

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编辑：KALYAN ACHARJYA 2018-11-29

在 MATLAB Online 中打开

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
    

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Answer 2

Bob Thompson 2018-11-29

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编辑：Bob Thompson 2018-11-29

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.