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Deleting rows where the value in a specific column match


 
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# 1  
Deleting rows where the value in a specific column match

Hi,

I have a tab delimited text file where I want to delete all rows that have the same string for column 1. How do I go about doing that? Thanks!

Example Input:
Code:
aa 1
aa 2
aa 3
bb 4
bc 5
bb 6
cd 8

Output:
Code:
bc 5
cd 8

# 2  
Given the number of threads you have started (and all that we hope you have learned from us), what have you tried so far?
# 3  
I've tried this:
Code:
 awk '!A[$1]++'

But if there are lines with repeating values in the first column, it still keeps the first line.
# 4  
Code:
awk '{a[$1]++;b[$1]=$0;next}END{for(i in a){ if(a[i]==1) print b[i] }}' file

This User Gave Thanks to Yoda For This Post:
# 5  
Find the pure prefixes and filter the file:
Code:
sort +0 -1 in_file | tee in_sort | sed 's/ .*//' | uniq -c | sed -n 's/^   1 //p' >in_uniq
join in_uniq in_sort > out_file

These problems of the fate of a line depending on a future line require storage or sorting, as going back is a bit hard. If you can cast it as a table, SQL is
Code:
select a.*
 from table a
  join (
    select field1
     from table
     group by field1
     having count(*) = 1
   ) b
  on b.field1 = a.field1


Last edited by DGPickett; 02-22-2013 at 06:11 PM..
 

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