How to delete/grab a line which matchs a pattern of a particular column only ?

mauludi · 01-18-2010, 12:27 AM

Dear All,

I indeed need your help. It is very importan for my research work.

I have found many information about how to delete/grab a line in a text file including delete line with match a pattern but I did not find info about how to delete a line which match a pattern of a particular column only.

for example mydata.txt:
id type x y z
1 6 0.474611 0.227223 0.583947
2 4 0.422894 0.22726 0.536791
3 5 0.448963 0.200148 0.560336
4 3 0.386478 0.207721 0.515293
5 6 0.371617 0.22361 0.582206
6 4 0.32123 0.222999 0.534782

so how to obtain data with type 4 only so that mydata.text file become:

id type x y z
2 4 0.422894 0.22726 0.536791
6 4 0.32123 0.222999 0.534782

and how to have data without type 3 , mydata.test file become:

id type x y z

1 6 0.474611 0.227223 0.583947
2 4 0.422894 0.22726 0.536791
3 5 0.448963 0.200148 0.560336
5 6 0.371617 0.22361 0.582206
6 4 0.32123 0.222999 0.534782

thank a lot in advance

Mauludi

Tinkster · 01-18-2010, 12:32 AM

Hi, welcome to LQ!

awk is the perfect tool for this kind of job.

It allows you to compare regex against column type data (e.g.,
whitespace delimited text like yours).

Code:

awk '$2 ~ /4/' file > new_file
awk '$2 !~ /3/' file > new_file

Cheers,
Tink

evo2 · 01-18-2010, 12:36 AM

Code:

awk '{ if ( $2==4 || FNR==1 ) print $0 }' mydata.text

This will print the first line or anyline when the 2nd column is 4.

Cheers,

Evo2.

mauludi · 01-18-2010, 01:13 AM

thank you for your quick reply,

but sorry for further question, how about obtain two type (for example 4 and 5) of my datafile.tx
id type x y z
1 6 0.474611 0.227223 0.583947
2 4 0.422894 0.22726 0.536791
3 5 0.448963 0.200148 0.560336
4 3 0.386478 0.207721 0.515293
5 6 0.371617 0.22361 0.582206
6 4 0.32123 0.222999 0.534782

so that it becomes :
2 4 0.422894 0.22726 0.536791
3 5 06 4 0.32123 0.222999 0.534782
6 4 0.32123 0.222999 0.534782

once agaiin thank you very much for your help

evo2 · 01-18-2010, 01:33 AM

Code:

awk '{ if ( $2==4 || $2==5 || FNR==1 ) print $0 }' mydata.text

Evo2.

Tinkster · 01-18-2010, 11:07 AM

You just don't need either the "if" or the "print".

Code:

awk '$2==4 || $2==5 || FNR==1' mydata.text

evo2 · 01-18-2010, 05:52 PM

Quote:

Originally Posted by Tinkster

You just don't need either the "if" or the "print".

Very true, but by including an example with them the OP will learn more.

Cheers,

EVo2.