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# 1  
Old 06-06-2013
Help with the awk syntax
Hello Experts:

While writing a script to help one of the posts on here, I end up writing a wrong one. I am very much eager to know how this can be corrected.
Aim was to not print specified columns - lets say out of 100 fields, need to print all but 5th, 10th, 15th columns.
Someone already answered it - $5=$10=$15="". This also should work.
I was thinking in another way to do it: Store the fields that needs to be excluded, in a separate file - nofields

Below is the script that I wrote:

awk 'NR==FNR{a[$1];next}{for (i = 1; i <= NF; i++)if(i not in a)print $i}' nofields input

I am sure there is mistakes in it, but interested in knowing what it is.
Last edited by juzz4fun; 06-06-2013 at 02:47 PM..
# 2  
Old 06-06-2013
Replace if(i not in a ) with if ( ! ( i in a ) )
This User Gave Thanks to Yoda For This Post:
juzz4fun
# 3  
Old 06-06-2013
That certainly worked.
But the o/p is like 1st fields on 1st line, 2nd field on 2nd line, 3rd is on 3rd line so on..
how can I avoid this?
# 4  
Old 06-06-2013
Replace print $i with printf (i==NF?$i RS:$i)
# 5  
Old 06-06-2013
Quote:
Originally Posted by Yoda
Replace print $i with printf (i==NF?$i RS:$i)
What if the last field is the one to be excluded from the output?
This User Gave Thanks to elixir_sinari For This Post:
Yoda
# 6  
Old 06-06-2013
Quote:
Originally Posted by juzz4fun
Hello Experts:

While writing a script to help one of the posts on here, I end up writing a wrong one. I am very much eager to know how this can be corrected.
Aim was not to print specified columns - lets say out of 100 fields, need to print all but 5th, 10th, 15th columns.
Someone already answered it - $5=$10=$15="". This also should work.
I was thinking in another way to do it: Store the fields that needs to be excluded, in a separate file - nofields

Below is the script that I wrote:

awk 'NR==FNR{a[$1];next}{for (i = 1; i <= NF; i++)if(i not in a)print $i}' nofields input

I am sure there is mistakes in it, but interested in knowing what it is.
Setting $5 $10 and $15 to null is the way to go but if you want to do it using an exclude file then here's how...
Code:
awk '{if (NR==FNR) a[$1]; else {for (i=1; i<=NF; i++) if (!(i in a)) printf("%s", i<NF ? $i FS : $i "\n")}' nofields input

Last edited by shamrock; 06-06-2013 at 03:03 PM.. Reason: Beaten by Yoda to the pip...
# 7  
Old 06-06-2013
Thanks all... I modified my script as below and it worked as expected.

nawk 'NR==FNR{a[$1];next}{for (i = 1; i <= NF; i++)if(!(i in a))printf("%s", i<NF ? $i FS : $i "\n")}' nofields input
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