awk to replace particular field

vgr12386 · 06-03-2009, 11:17 AM

awk to replace particular field
i have bad data for instance, the use of capital letters in the middle of the word.
I identified the errors, made a list and put it in a file error_correction.txt
Incorrect,Correct
VeNOM,Venom
nos,NOS
.
.
.

My data file looks like this:
vgr,bugatti veron,,3.5,Venom,6,.......,....
vgr,lamborgini,,3.5,nos,6,.......,....
abc,bugatti veron,,3.5,Venom,6,.......,.......
.
.
.
.

I need to replace the terms in a the 5th field with that from the file.
How do i do this using awk??
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Disillusionist · 06-03-2009, 02:56 PM

This screams homework to me, however here is a start for you:

Code:

awk -F',' -vOFS=',' '( $5 == v_test ) {$5 = v_replace} {print} ' v_test=VeNOM v_replace=Venom data_file

ghostdog74 · 06-03-2009, 07:36 PM

Code:

awk -F"," 'FNR==NR{a[$1]=$2;next}
( $5 in a ){
     $5=a[$5]; 
     #<do something 
}' error_correction file

vgr12386 · 06-04-2009, 06:45 AM

There seemed to be one problem.
The value seemed to be changing inside the loop but the files remained unchanged!
The change was not being saved.
How do i save it?

colucix · 06-04-2009, 08:16 AM

awk cannot change the input file. You have to redirect the output to a new file and then rename it as the original one:

Code:

$ awk blah blah blah input_file > output_file
$ mv output_file input_file

vgr12386 · 06-04-2009, 09:01 AM

thanks man

vgr12386 · 06-05-2009, 05:01 AM

hey is it possible to use two delimiters for example , for one file and ; for the other?

vgr12386 · 06-05-2009, 05:19 AM

Quote:

Originally Posted by colucix

awk cannot change the input file. You have to redirect the output to a new file and then rename it as the original one:

Code:

$ awk blah blah blah input_file > output_file
$ mv output_file input_file

Hey when i do this,
the field seprater ie. "," is being removed!
The line i get is seprated only by spaces

colucix · 06-05-2009, 07:14 AM

Well, the program "blah blah blah" does not work, indeed!

Seriously now: if you want a comma as Output Field Separator you have to specify it using:

Code:

BEGIN{OFS=","}

at the beginning of the awk program. Please, post the actual code you're using, if you need more advices.

colucix · 06-05-2009, 07:15 AM

Quote:

Originally Posted by vgr12386

hey is it possible to use two delimiters for example , for one file and ; for the other?

I don't really know, but maybe after the "next" statement you can change the value of FS (the input field separator). Again, please re-post the input files and the awk code you're using now. Thx.