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Re^2: Perl - Remove duplicate based on substring and check on delimiters

by AnomalousMonk (Bishop)
on May 19, 2016 at 01:54 UTC ( #1163394=note: print w/replies, xml ) Need Help??


in reply to Re: Perl - Remove duplicate based on substring and check on delimiters
in thread Perl - Remove duplicate based on substring and check on delimiters

That gives an off-by-one  $tokens value (it's actually counting the stuff "around" the tokens (update: and it requires creation of an otherwise unused array to hold most of that stuff)), but that's easy to fix:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le "my $t = 'x'; ;; for my $line (qw( 1212123x534534534534xx4545454x232322xx 0901001x876879878787xx0909918x212245xx 1212123x534534534534xx4545454x232323xx 1212133x534534534534xx4549454x232322xx 4352342xx23232xxx345545x45454x23232xxx )) { my $tokens = my ($first, @rest) = split $t, $line, -1; $tokens -= 1; print qq{'$line': num '$t' tokens is: $tokens}; dd ($first, \@rest); } " '1212123x534534534534xx4545454x232322xx': num 'x' tokens is: 6 (1212123, [534534534534, "", 4545454, 232322, "", ""]) '0901001x876879878787xx0909918x212245xx': num 'x' tokens is: 6 ("0901001", [876879878787, "", "0909918", 212245, "", ""]) '1212123x534534534534xx4545454x232323xx': num 'x' tokens is: 6 (1212123, [534534534534, "", 4545454, 232323, "", ""]) '1212133x534534534534xx4549454x232322xx': num 'x' tokens is: 6 (1212133, [534534534534, "", 4549454, 232322, "", ""]) '4352342xx23232xxx345545x45454x23232xxx': num 'x' tokens is: 10 ( 4352342, ["", 23232, "", "", 345545, 45454, 23232, "", "", ""], )
(But I don't really see anything wrong with using good old  tr/// for counting and poor old substr for fixed-field extraction.)

Update: This gets rid of  @rest and the  $tokens -= 1; statement for all you one-liner addicts out there:
    my $tokens = (my ($first) = split $t, $line, -1) - 1;


Give a man a fish:  <%-{-{-{-<

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Re^3: Perl - Remove duplicate based on substring and check on delimiters
by Marshall (Canon) on May 19, 2016 at 02:52 UTC
    I think we are splitting hairs here. I count $first as the first token, you don't. Or you figure that the final empty token shouldn't be counted? Either way not a significant problem in my mind.

    Yes, tr is the fastest and best way to do a simple count of the x's. And yes, substr is the fastest way to get a fixed length thing at the beginning. The reason that I demo'd split was to show: a)how to get a non-fixed length thing at the beginning, b)how to access some of these other length "between the x's" fields. I'm sure that they have some meaning.

    Update: I almost never use the -1 limit on split. I saw an opportunity to play with this and remind myself of how it worked. Once I had done that, I impulsively posted my "play". Wasn't meant to be "earth shattering" stuff, just an example of a not so common usage that is often forgotten.

      ... do a simple count of the x's. ... get a fixed length thing at the beginning.

      But I understood that to be what the OP was asking for, at least as a starting point for a larger application. (bopibopi actually seemed to have the counting and extracting part under control, and was asking for help with the subsequent pieces.) Using split may be a good example of doing something slightly different. We may not be so much splitting hairs here as comparing apples and oranges — or perhaps tangerines and oranges since we're not really all that far apart.

      Update:

      ... the -1 limit on split ... an example of a not so common usage ...
      As someone addicted to "not so common usage" myself, I can sympathize. (But I have it under control; I haven't used uncommonly in ages!)


      Give a man a fish:  <%-{-{-{-<

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