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Assign regular expression change to only first two columns

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# 1  
Old 12-19-2010
Assign regular expression change to only first two columns
input
Code:
1_2  2_3  4_4  4_5
2_2  4_5  4_4  5_5

output
Code:
1  2  2  3  4_4  4_5
2  2  4  5  4_4  5_5

I used the following command but it changes every column. i just want to change first two.

Code:
tr '_' '\t'

# 2  
Old 12-20-2010
Quote:
Originally Posted by quincyjones
I used the following command but it changes every column. i just want to change first two.
Code:
awk '{sub(/_/,FS,$1);sub(/_/,FS,$2)}1' file

This User Gave Thanks to danmero For This Post:
quincyjones
# 3  
Old 12-20-2010
Code:
sed 's/_/ /;s/_/ /' file

This User Gave Thanks to Scrutinizer For This Post:
quincyjones
# 4  
Old 12-20-2010
Quote:
Originally Posted by Scrutinizer
Code:
sed 's/_/ /;s/_/ /' file

Your solution apply for the first two occurrences not
Quote:
Originally Posted by quincyjones
Assign regular expression change to only first two columns
# 5  
Old 12-20-2010
you can try this also -
Code:
cat <file> | sed 's/_/ /1'| sed 's/_/ /1'

Last edited by Scott; 12-20-2010 at 07:56 AM.. Reason: Code tags
# 6  
Old 12-20-2010
Quote:
Originally Posted by danmero
Code:
awk '{sub(/_/,FS,$1);sub(/_/,FS,$2)}1' file

If any "column" has more than one occurrence then your solution would fail also, given the expected output. The FS is probably useful, though Smilie

Quote:
Originally Posted by adc22
you can try this also -
Code:
cat <file> | sed 's/_/ /1'| sed 's/_/ /1'

No need for cat, and using 1 is the same as not using g, which is the same as Scrutinizer already posted.
# 7  
Old 12-20-2010
Quote:
Originally Posted by scottn
If any "column" has more than one occurrence then your solution would fail also, given the expected output.
That's correct , let's try
Code:
awk '{gsub(/_/,FS,$1);gsub(/_/,FS,$2)}1' file


This following two solution will fail if first OR second OR both target column's don have the special char OR the target column's have more that one occurrence of special char.
Code:
sed 's/_/ /1'| sed 's/_/ /1' file

Code:
sed 's/_/ /;s/_/ /' file
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