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Full Discussion: Finding maximum occurrence value using awk
Top Forums UNIX for Beginners Questions & Answers Answers to Frequently Asked Questions Finding maximum occurrence value using awk Post 302788219 by meet77 on Monday 1st of April 2013 09:42:59 AM
Old 04-01-2013
Finding maximum occurrence value using awk
Hi everyone, I'm a new member at the forum
I have a file like this: field 2 values are either 0 or negative. file test4:

Code:
100815    -20
118125    0
143616    0
154488    0
154488    0
154488    -6
196492    -5
196492    -9
196492    -7
27332    0
29397    0

I would like to print a line containing the maximum value in field 2 of all occurrences for each value in field 1. So the desired output should be:

Code:
100815    -20
118125    0
143616    0
154488    0
196492    -5
27332    0
29397    0

I am using awk to do this. But, there are two problems: first awk prints nothing when I try to get the maximum for the values with negative numbers but it has no problem when I try the same with positive numbers. This made me take the absolute values which I can later turn back to the original values. The second problem, I get the following output with my code:

Code:
100815    20
118125    0
143616    0
154488    6
196492    7
27332    0
29397    0

Although with absolute values I should get:

Code:
100815    20
118125    0
143616    0
154488    0
196492    5
27332    0
29397    0

My code is:
awk '{$2>0?$2=$2:$2=-$2} $2==0 {$2=0} {print}' test4 | awk 'NR==1 {a[$1]=$2} {a[$1]=$2 ; if ($2<a[$1]) a[$1]=$2; else a[$1]=a[$1];} END {for(i in a) print i"\t"a[i];}'

I am sure I'm missing something basic and this could probably be done in a much simpler way. Any help is appreciated
Best reagrds to all
Last edited by joeyg; 04-01-2013 at 10:48 AM.. Reason: Please wrap data and commands inside CodeTags
 

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LEARN ABOUT DEBIAN

dpkg-awk

DPKG-AWK(1)						      General Commands Manual						       DPKG-AWK(1)

NAME

       dpkg-awk - Utility to read a dpkg style db file

SYNOPSIS

       dpkg-awk [(-f|--file) filename] [(-d|--debug) ##] [(-s|--sort) list] [(-rs|--rec_sep) ??] '<fieldname>:<regex>' ... -- <out_fieldname> ..

DESCRIPTION

       dpkg-awk  Parses  a  dpkg status file (or other similarly formatted file) and outputs the resulting records.  It can use regex on the field
       values to limit the returned records, it can also be told which fields to output, and it can sort the matched fields.

OPTIONS

       -f filename
       --file filename
	      The file to parse.  The default is /var/lib/dpkg/status.

       -d [#]
       --debug [#]
	      Each time this is specified, it increased the debug level.

       -s field(s)
       --sort field(s)
	      A space or comma separated list of fields to sort on.

       -n field(s)
       --numeric field(s)
	      A space or comma separated list of fields that should be interpreted as numeric in value.

       -rs ??
       --rec_sep ??
	      Output this string at the end of each output paragraph.

       -h
       --help Display some help.

       fieldname
	      The fields from the file, that are matched with the regex given.	The fieldnames are case insensitive.

       out_fieldname
	      The fields from the file, that are output for each record.  If the first field listed begins with ^, then the list  of  fields  that
	      follows will NOT be output.

BUGS

       Be  warned  that  the author has only a shallow understanding of the dpkg packaging system, so there are probably tons of bugs in this pro-
       gram.

       This program comes with no warranties.  If running this program causes fire and brimstone to rain down upon the earth, you will be on  your
       own.

       This program accesses the dpkg database directly in places, querying for data that cannot be gotten via dpkg.

AUTHOR

       Adam Heath <doogie@debian.org>

DEBIAN
								 Debian Utilities						       DPKG-AWK(1)
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