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awk uniq and longest string of a column as index

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# 8  
Old 09-13-2012
awk uniq and longest string of a column as index
Thanks vgersh99!
The key point is the substring of the current line to any of the lines that have been read. Kind of recursively comparison.
What's in my mind is:
Code:
read in line;
compare current line to the old ones;
If it is new, remember it;
If it is longer than any of the memory (i.e. any member of the memory is substring of current line), replace the old one with current line;
if it is a substring of any of the memory, ignore current one;

as awk is processing one line at a time, I thought it is good to handle this problem.
Code:
If it is new, remember it;

may not be accurate. Each line for sure is a unique string, but can be substring/"parent"string of other.
Thanks a lot!
yi
Last edited by yifangt; 09-13-2012 at 10:33 AM.. Reason: bug of the algorithm
# 9  
Old 09-13-2012
still a bit vague, but getting your desired output and probably not the most efficient one given the amount of data....
awk -f yi.awk myFile
yi.awk:
Code:
{a[$0]}
END {
  for (i in a)
    for (j in a)
      if (length(i) > length(j) && i ~ j)
        delete a[j]

  for (i in a)
    print i
}

Last edited by vgersh99; 09-13-2012 at 11:17 AM..
# 10  
Old 09-13-2012
Can I ask why need i<=255?
# 11  
Old 09-13-2012
Quote:
Originally Posted by yifangt
Can I ask why need i<=255?
huh? I don't see any mention of '255' in my most recent posting.
The mention of '255' was in the post where I didn't quite understand what you're after - try the most recent post/solution.
# 12  
Old 09-13-2012
Quote:
Originally Posted by vgersh99
Code:
i ~ j

It's probably a good idea to avoid regular expressions. If the real data can contain regular expression metacharacters, they could lead to an erroneous result. Even if the data is strictly alphabetical (as in the sample data), it might be a little bit faster to just use index(i,j).

Regards,
Alister
# 13  
Old 09-13-2012
Quote:
Originally Posted by alister
It's probably a good idea to avoid regular expressions. If the real data can contain regular expression metacharacters, they could lead to an erroneous result. Even if the data is strictly alphabetical (as in the sample data), it might be a little bit faster to just use index(i,j).

Regards,
Alister
nice 'nit-picking' - good idea! Smilie
Thanks
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