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Old 05-10-2011, 04:02 PM   #1
Sourav_Das
LQ Newbie
 
Registered: May 2011
Posts: 2

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Maximum Date Value from a file


Hi ..

I am facing a problem in finding out the maximum value of a field using awk .. The field is of date format i.e. (MM/DD/YYYY) ..

The contents of the file is :

2/2/2011 XYZ
2/2/2011 XYZ1
2/3/2011 ABC
2/4/2011 ABC
.
.
.
2/9/2011 XYZ
2/10/2011 XYZ
2/11/2011 XYZ
2/12/2011 XYZ

I need to find the maximum of the first column i.e. my output should be 2/12/2011 ..

I was using the below awk script :
awk 'n < $0 {n=$0} {print n}{print $0}' <source_file having the above data>

But the output I am getting is 2/9/2011 instead of 2/12/2011 ...

Can anyone please tell me as what could be reason for this output and how can I get my desired result ..?

Regards,
Sourav
 
Old 05-10-2011, 04:08 PM   #2
SL00b
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Registered: Feb 2011
Location: LA, US
Distribution: SLES
Posts: 375

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Alignment.

One method to resolve this would be to re-format your date fields so they're padded with left zeroes, like so:

02/02/2011 XYZ
02/02/2011 XYZ1
02/03/2011 ABC
02/04/2011 ABC
...
02/09/2011 XYZ
02/10/2011 XYZ
02/11/2011 XYZ
02/12/2011 XYZ

And you should be good to go.

If you're not padding left zeroes, you're not truly in MM/DD/YYYY format.

The next option would be beyond my skill set... you'd have to figure out how to use the / character as a delimiter.
 
Old 05-10-2011, 06:00 PM   #3
Tinkster
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Registered: Apr 2002
Location: in a fallen world
Distribution: slackware by choice, others too :} ... android.
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Just a word of caution; this will only work if there's always ever only
ONE months worth of dates from the SAME year in the file:
Code:
awk -F"[/ ]" 'BEGIN{oldd=""}{if(oldd<$2){p=$0;oldd=$2}}END{print p}' sourav
2/12/2011 XYZ


Cheers,
Tink

Last edited by Tinkster; 05-10-2011 at 06:04 PM.
 
Old 05-23-2011, 10:09 PM   #4
Sourav_Das
LQ Newbie
 
Registered: May 2011
Posts: 2

Original Poster
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Thanks for your replies ... Sorry for the delay in replying ...

To SL00b,
I finally thought of going to the route u suggested by having all the dates in format MM/DD/YYYY , it was working fine till I encountered the below dates in the file

12/31/2010
01/01/2011

I was expecting an O/P 01/01/2011 but the script gave 12/31/2010.. Can anyone please help?
 
  


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