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Parsing a CSV file and deleting all rows on condition

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# 1  
Old 06-07-2011
Java Parsing a CSV file and deleting all rows on condition
Hello list,

I am working on a csv file which contains two fields per record which contain IP addresses. What I am trying to do is find records which have identical fields(IP addresses) which occur 4(four) times, and if they do, delete all records with that specific identical field(ip address).

for example, the csv looks like this:
Code:
field 1,192.168.1.1,field 3, 192.168.1.128
field 1,192.168.1.1,field 3, 192.168.1.128
field 1,192.168.1.1,field 3, 192.168.1.128
field 1,192.168.1.1,field 3, 192.168.1.128
field 1,10.10.10.1,field 3, 192.168.1.128
field 1,172.16.10.1,field 3, 192.168.1.128
field 1,10.10.10.3,field 3, 192.168.1.128

so I want to parse the csv and delete the following rows where the ip address in field 2 is identical for 4 occurrences:
Code:
field 1,192.168.1.1,field 3, 192.168.1.128
field 1,192.168.1.1,field 3, 192.168.1.128
field 1,192.168.1.1,field 3, 192.168.1.128
field 1,192.168.1.1,field 3, 192.168.1.128

any ideas?

thanks.
Last edited by Franklin52; 06-08-2011 at 04:01 AM.. Reason: Please use code tags
# 2  
Old 06-07-2011
Code:
awk -F , 'NR==FNR{a[$0]++;next} a[$0]<4' infile infile

field 1,10.10.10.1,field 3, 192.168.1.128
field 1,172.16.10.1,field 3, 192.168.1.128
field 1,10.10.10.3,field 3, 192.168.1.128

This User Gave Thanks to rdcwayx For This Post:
landossa
# 3  
Old 06-08-2011
hi rdcwayx,

I tried this but can't seem to get it to work. Also I've only got one infile, so I'm not comparing two different files, but rather comparing records, and if there are 4 records with the exact same field value for one of the specific fields, then deleting all four records. Something like an < infile > outfile function.
# 4  
Old 06-08-2011
Try this, Pass input file twice
Code:
awk -F"," 'NR==FNR{a[$2]=a[$2]+1;next}a[$2]<4' infile infile >outfile

This User Gave Thanks to pravin27 For This Post:
landossa
# 5  
Old 06-08-2011
it works!
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