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Re: [PBML] Alphabetize a word

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  • Paul Archer
    The slashes delimit a regular expression. In this case, the regexp is empty. Using an empty regular expression for the split means that each character will
    Message 1 of 15 , Sep 5, 2007
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      The slashes delimit a regular expression. In this case, the regexp is empty.
      Using an empty regular expression for the split means that each character
      will become a separate element in our array.

      Paul


      10:21am, Ryan J Nauman wrote:

      > What does the pattern " //" break down to? I'm somewhat familiar with
      > regular expressions and don't know what a forward slash does. I would
      > have guessed the matching pattern would've been the "." character that
      > matches any character (except \n).
      >
      >
      >
      >
      > Paul Archer <tigger@...>
      > Sent by: perl-beginner@yahoogroups.com
      > 09/05/2007 10:12 AM
      > Please respond to
      > perl-beginner@yahoogroups.com
      >
      >
      > To
      > perl-beginner@yahoogroups.com
      > cc
      >
      > Subject
      > Re: [PBML] Alphabetize a word
      >
      >
      >
      >
      >
      >
      > Which gets us to the oneliner:
      > perl -e ' $word="alphabetize"; print join "", (sort split ( //, $word)),
      > "\n"'
      >
      > 1:41pm, greenberg.d@... wrote:
      >
      >> As for returning it as a string instead of an array of characters, look
      > at the "join" function. With it, you can explicitly return a string.
      >>
      >> -David
      >>
      >> Sent via BlackBerry by AT&T
      >>
      >> -----Original Message-----
      >> From: Paul Archer <tigger@...>
      >>
      >> Date: Wed, 5 Sep 2007 08:20:52
      >> To:perl-beginner@yahoogroups.com
      >> Subject: Re: [PBML] Alphabetize a word
      >>
      >>
      >> If what you are looking for is a list of the letters in a word, in
      >> alphabetical order, then you want something like:
      >>
      >> perl -e ' $word="alphabetize"; @array= sort split ( //, $word); print
      >> @array, "\n"'
      >>
      >> And you're doing fine with the 'shift'. No reason not to do it just the
      > way
      >> you have it.
      >>
      >> Paul
      >>
      >> 9:13am, Ryan J Nauman wrote:
      >>
      >>> I wrote the following code to alphabetize a word:
      >>>
      >>> sub alphabetize
      >>> {
      >>> my $word = uc(shift);
      >>> my $wordlen = length($word);
      >>> my @letters;
      >>>
      >>> for (my $i = 0; $i < length $word; $i++)
      >>> {
      >>> push @letters, substr($word, $i, 1);
      >>> }
      >>>
      >>> @letters = sort @letters;
      >>> return @letters;
      >>> }
      >>>
      >>> This function will always only receive one parameter. In this case I
      > do
      >>> not know if shift is the best method or not. $_ was not giving me
      >>> anything so I went with shift. Alternatively, I think I could've used
      > @_.
      >>> Does it matter?
      >>>
      >>> If it can be optimized in any way I would appreciate pointers. My
      >>> ultimate question though is I want it to return a string instead of
      > the
      >>> sorted character array that it is now. I can write it using a for loop
      >>> and string concatenation but I think that would be extremely
      > inefficient.
      >>> Help appreciated!
      >>>
      >>>
      >>> [Non-text portions of this message have been removed]
      >>>
      >>>
      >>
      >> ---------------------------
      >> 404 Error - Item Not Found
      >> <haiku>
      >> You step in the stream,
      >> but the water has moved on.
      >> That page is not here.
      >> </haiku>
      >> ---------------------------
      >>
      >> -----11004 days until retirement!-----
      >>
      >>
      >> Unsubscribing info is here:
      > http://help.yahoo.com/help/us/groups/groups-32.html
      >> Yahoo! Groups Links
      >>
      >>
      >>
      >>
      >>
      >
      > __________________________________________________________
      > "Can't you recognize bullshit? Don't you think it would be a
      > useful item to add to your intellectual toolkits to be capable
      > of saying, when a ton of wet steaming bullshit lands on your
      > head, 'My goodness, this appears to be bullshit'?
      > _____________Neal Stephenson, "Cryptonomicon"__________________
      >
      > -----11004 days until retirement!-----
      >
      >
      >
      > [Non-text portions of this message have been removed]
      >
      >



      ---------------------------------------------------------
      "You will always be lucky if you know how to make friends
      with strange cats." - Colonial American proverb
      ---------------------------------------------------------

      -----11004 days until retirement!-----
    • Ryan J Nauman
      Ah, thanks. Neat little trick. Well I finished my first complete working version of the code and is a bit sluggish. Though this is expected since the input
      Message 2 of 15 , Sep 5, 2007
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        Ah, thanks. Neat little trick. Well I finished my first complete working
        version of the code and is a bit sluggish. Though this is expected since
        the input file contains about 170,000 words stuffed into my @WORDS array.
        Wondering if you guys know any tricks to speed things up anywhere? Here
        is a link to my source code: http://pastie.textmate.org/94246

        Ryan




        Paul Archer <tigger@...>
        Sent by: perl-beginner@yahoogroups.com
        09/05/2007 11:28 AM
        Please respond to
        perl-beginner@yahoogroups.com


        To
        perl-beginner@yahoogroups.com
        cc

        Subject
        Re: [PBML] Alphabetize a word






        The slashes delimit a regular expression. In this case, the regexp is
        empty.
        Using an empty regular expression for the split means that each character
        will become a separate element in our array.

        Paul

        10:21am, Ryan J Nauman wrote:

        > What does the pattern " //" break down to? I'm somewhat familiar with
        > regular expressions and don't know what a forward slash does. I would
        > have guessed the matching pattern would've been the "." character that
        > matches any character (except \n).
        >
        >
        >
        >
        > Paul Archer <tigger@...>
        > Sent by: perl-beginner@yahoogroups.com
        > 09/05/2007 10:12 AM
        > Please respond to
        > perl-beginner@yahoogroups.com
        >
        >
        > To
        > perl-beginner@yahoogroups.com
        > cc
        >
        > Subject
        > Re: [PBML] Alphabetize a word
        >
        >
        >
        >
        >
        >
        > Which gets us to the oneliner:
        > perl -e ' $word="alphabetize"; print join "", (sort split ( //, $word)),
        > "\n"'
        >
        > 1:41pm, greenberg.d@... wrote:
        >
        >> As for returning it as a string instead of an array of characters, look
        > at the "join" function. With it, you can explicitly return a string.
        >>
        >> -David
        >>
        >> Sent via BlackBerry by AT&T
        >>
        >> -----Original Message-----
        >> From: Paul Archer <tigger@...>
        >>
        >> Date: Wed, 5 Sep 2007 08:20:52
        >> To:perl-beginner@yahoogroups.com
        >> Subject: Re: [PBML] Alphabetize a word
        >>
        >>
        >> If what you are looking for is a list of the letters in a word, in
        >> alphabetical order, then you want something like:
        >>
        >> perl -e ' $word="alphabetize"; @array= sort split ( //, $word); print
        >> @array, "\n"'
        >>
        >> And you're doing fine with the 'shift'. No reason not to do it just the
        > way
        >> you have it.
        >>
        >> Paul
        >>
        >> 9:13am, Ryan J Nauman wrote:
        >>
        >>> I wrote the following code to alphabetize a word:
        >>>
        >>> sub alphabetize
        >>> {
        >>> my $word = uc(shift);
        >>> my $wordlen = length($word);
        >>> my @letters;
        >>>
        >>> for (my $i = 0; $i < length $word; $i++)
        >>> {
        >>> push @letters, substr($word, $i, 1);
        >>> }
        >>>
        >>> @letters = sort @letters;
        >>> return @letters;
        >>> }
        >>>
        >>> This function will always only receive one parameter. In this case I
        > do
        >>> not know if shift is the best method or not. $_ was not giving me
        >>> anything so I went with shift. Alternatively, I think I could've used
        > @_.
        >>> Does it matter?
        >>>
        >>> If it can be optimized in any way I would appreciate pointers. My
        >>> ultimate question though is I want it to return a string instead of
        > the
        >>> sorted character array that it is now. I can write it using a for loop
        >>> and string concatenation but I think that would be extremely
        > inefficient.
        >>> Help appreciated!
        >>>
        >>>
        >>> [Non-text portions of this message have been removed]
        >>>
        >>>
        >>
        >> ---------------------------
        >> 404 Error - Item Not Found
        >> <haiku>
        >> You step in the stream,
        >> but the water has moved on.
        >> That page is not here.
        >> </haiku>
        >> ---------------------------
        >>
        >> -----11004 days until retirement!-----
        >>
        >>
        >> Unsubscribing info is here:
        > http://help.yahoo.com/help/us/groups/groups-32.html
        >> Yahoo! Groups Links
        >>
        >>
        >>
        >>
        >>
        >
        > __________________________________________________________
        > "Can't you recognize bullshit? Don't you think it would be a
        > useful item to add to your intellectual toolkits to be capable
        > of saying, when a ton of wet steaming bullshit lands on your
        > head, 'My goodness, this appears to be bullshit'?
        > _____________Neal Stephenson, "Cryptonomicon"__________________
        >
        > -----11004 days until retirement!-----
        >
        >
        >
        > [Non-text portions of this message have been removed]
        >
        >

        ---------------------------------------------------------
        "You will always be lucky if you know how to make friends
        with strange cats." - Colonial American proverb
        ---------------------------------------------------------

        -----11004 days until retirement!-----



        [Non-text portions of this message have been removed]
      • merlyn@stonehenge.com
        ... Ryan Ah, thanks. Neat little trick. Well I finished my first complete working Ryan version of the code and is a bit sluggish. Though this is expected
        Message 3 of 15 , Sep 5, 2007
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          >>>>> "Ryan" == Ryan J Nauman <RJNauman@...> writes:

          Ryan> Ah, thanks. Neat little trick. Well I finished my first complete working
          Ryan> version of the code and is a bit sluggish. Though this is expected since
          Ryan> the input file contains about 170,000 words stuffed into my @WORDS array.
          Ryan> Wondering if you guys know any tricks to speed things up anywhere? Here
          Ryan> is a link to my source code: http://pastie.textmate.org/94246

          Ooof, yeah. You're doing an exponential matching O(n squared)
          instead of just stashing everything according to its anagram.

          You need to use a "bucket" approach. As you compute each anagram,
          dump the original word into a bucket keyed by anagram, using a hash
          of arrayrefs...

          my %buckets;
          for my $word (@words) {
          my $alphaword = alphabetize($word);
          push @{$bucket{$alphaword}}, $word;
          }

          Now it's simply a matter of dumping each bucket:

          for my $alphaword (sort keys %bucket) {
          my $aref = $bucket{$alphaword};
          print "@$aref\n";
          }

          That will be infinitely faster when you get above a few hundred words.

          --
          Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
          <merlyn@...> <URL:http://www.stonehenge.com/merlyn/>
          Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
          See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl training!
        • Ryan J Nauman
          Ah, excellent. However, allow my noobness to kick in. Alright so you want me to create a hash that contains the entire list of words (values) associated with
          Message 4 of 15 , Sep 5, 2007
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            Ah, excellent. However, allow my noobness to kick in. Alright so you
            want me to create a hash that contains the entire list of words (values)
            associated with their alphabetized version (keys)? Should I do this as
            soon as I read in the input file? And should I continue with the line of
            code "my @WORDS = <INFILE>;" and create the bucket directly after?

            Now for the "dumping each bucket" portion I don't follow. Assuming I am
            following correctly on the first part, you're sorting the hash we made in
            the first step correct? I don't understand the print line. And is this
            used solely for sorting our newly created hash and then using my
            conditions against this new word list?

            Once the "bucket" hash is created would it be beneficial to my programs
            memory/execution time to close the INFILE and is there a way to delete the
            original @WORDS array now that the improved hash is in place?

            Thanks,
            Ryan




            merlyn@...
            Sent by: perl-beginner@yahoogroups.com
            09/05/2007 12:36 PM
            Please respond to
            perl-beginner@yahoogroups.com


            To
            Ryan J Nauman <RJNauman@...>
            cc
            perl-beginner@yahoogroups.com
            Subject
            Re: [PBML] Alphabetize a word






            >>>>> "Ryan" == Ryan J Nauman <RJNauman@...> writes:

            Ryan> Ah, thanks. Neat little trick. Well I finished my first complete
            working
            Ryan> version of the code and is a bit sluggish. Though this is expected
            since
            Ryan> the input file contains about 170,000 words stuffed into my @WORDS
            array.
            Ryan> Wondering if you guys know any tricks to speed things up anywhere?
            Here
            Ryan> is a link to my source code: http://pastie.textmate.org/94246

            Ooof, yeah. You're doing an exponential matching O(n squared)
            instead of just stashing everything according to its anagram.

            You need to use a "bucket" approach. As you compute each anagram,
            dump the original word into a bucket keyed by anagram, using a hash
            of arrayrefs...

            my %buckets;
            for my $word (@words) {
            my $alphaword = alphabetize($word);
            push @{$bucket{$alphaword}}, $word;
            }

            Now it's simply a matter of dumping each bucket:

            for my $alphaword (sort keys %bucket) {
            my $aref = $bucket{$alphaword};
            print "@$aref\n";
            }

            That will be infinitely faster when you get above a few hundred words.

            --
            Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777
            0095
            <merlyn@...> <URL:http://www.stonehenge.com/merlyn/>
            Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
            See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl
            training!



            [Non-text portions of this message have been removed]
          • Ryan J Nauman
            Can someone please help me understand what is being explained here? I thought I understood it after looking at it a second time but the part that confuses me
            Message 5 of 15 , Sep 7, 2007
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              Can someone please help me understand what is being explained here? I
              thought I understood it after looking at it a second time but the part
              that confuses me now is the declare of "my %buckets" but we never use it,
              we use a scalar called $bucket. So, now I am completely lost.

              If someone could break it down, it'd be much appreciated.

              ------------------------
              Ryan



              merlyn@... (Randal L. Schwartz)
              09/05/2007 12:36 PM

              To
              Ryan J Nauman <RJNauman@...>
              cc
              perl-beginner@yahoogroups.com
              Subject
              Re: [PBML] Alphabetize a word






              >>>>> "Ryan" == Ryan J Nauman <RJNauman@...> writes:

              Ryan> Ah, thanks. Neat little trick. Well I finished my first complete
              working
              Ryan> version of the code and is a bit sluggish. Though this is expected
              since
              Ryan> the input file contains about 170,000 words stuffed into my @WORDS
              array.
              Ryan> Wondering if you guys know any tricks to speed things up anywhere?
              Here
              Ryan> is a link to my source code: http://pastie.textmate.org/94246

              Ooof, yeah. You're doing an exponential matching O(n squared)
              instead of just stashing everything according to its anagram.

              You need to use a "bucket" approach. As you compute each anagram,
              dump the original word into a bucket keyed by anagram, using a hash
              of arrayrefs...

              my %buckets;
              for my $word (@words) {
              my $alphaword = alphabetize($word);
              push @{$bucket{$alphaword}}, $word;
              }

              Now it's simply a matter of dumping each bucket:

              for my $alphaword (sort keys %bucket) {
              my $aref = $bucket{$alphaword};
              print "@$aref\n";
              }

              That will be infinitely faster when you get above a few hundred words.

              --
              Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777
              0095
              <merlyn@...> <URL:http://www.stonehenge.com/merlyn/>
              Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
              See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl
              training!



              [Non-text portions of this message have been removed]
            • Ryan J Nauman
              I have the following code for pushing a new value onto my hash: my %buckets; push(@{ $buckets{ KEYNAME } }, new value ); my @keys = keys %buckets; my @values
              Message 6 of 15 , Sep 7, 2007
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                I have the following code for pushing a new value onto my hash:

                my %buckets;
                push(@{ $buckets{"KEYNAME"} }, "new value");
                my @keys = keys %buckets;
                my @values = values %buckets;
                print %buckets;
                print "\n@keys[0] => @values[0]";

                This code yields the following output...

                KEYNAMEARRAY(0x15d702c)
                KEYNAME => ARRAY(0x15d702c)

                Why won't it print "new value" ???

                I'm running perl, v5.8.8 build 822 from ActiveState.

                [Non-text portions of this message have been removed]
              • bike2ride
                ... With use strict; use warnings; you get the hint that you are not using Perl properly. Scalar value @keys[0] better written as $keys[0] at t.pl line 10.
                Message 7 of 15 , Sep 7, 2007
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                  --- In perl-beginner@yahoogroups.com, Ryan J Nauman <RJNauman@...> wrote:
                  >
                  > I have the following code for pushing a new value onto my hash:
                  >
                  > my %buckets;
                  > push(@{ $buckets{"KEYNAME"} }, "new value");
                  > my @keys = keys %buckets;
                  > my @values = values %buckets;
                  > print %buckets;
                  > print "\n@keys[0] => @values[0]";
                  >
                  > This code yields the following output...
                  >
                  > KEYNAMEARRAY(0x15d702c)
                  > KEYNAME => ARRAY(0x15d702c)
                  >
                  > Why won't it print "new value" ???
                  >
                  > I'm running perl, v5.8.8 build 822 from ActiveState.
                  >
                  > [Non-text portions of this message have been removed]
                  >

                  With

                  use strict;
                  use warnings;

                  you get the hint that you are not using Perl properly.

                  Scalar value @keys[0] better written as $keys[0] at t.pl line 10.
                  Scalar value @values[0] better written as $values[0] at t.pl line 10.


                  my %bucket = (
                  KEYNAME => 'new value',
                  ANOTHER => 'another value',
                  );

                  foreach my $key (keys %bucket) {
                  print "key = $key, value = $bucket{$key}\n";
                  }

                  for more information -> web search "perl hash howto"

                  gl
                • a_z0_9_blah
                  ... Because $values[0] is an array reference. Try: print n$keys[0] = $values[0][0] ; If you want a better explanation, see:
                  Message 8 of 15 , Sep 7, 2007
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                    --- In perl-beginner@yahoogroups.com, Ryan J Nauman <RJNauman@...>
                    wrote:
                    >
                    > I have the following code for pushing a new value onto my hash:
                    >
                    > my %buckets;
                    > push(@{ $buckets{"KEYNAME"} }, "new value");
                    > my @keys = keys %buckets;
                    > my @values = values %buckets;
                    > print %buckets;
                    > print "\n@keys[0] => @values[0]";
                    >
                    > This code yields the following output...
                    >
                    > KEYNAMEARRAY(0x15d702c)
                    > KEYNAME => ARRAY(0x15d702c)
                    >
                    > Why won't it print "new value" ???

                    Because $values[0] is an array reference.

                    Try:
                    print "\n$keys[0] => $values[0][0]";

                    If you want a better explanation, see:
                    http://perldoc.perl.org/perldsc.html

                    (which wiil also lead you to several other manual pages to
                    understand Perls datastructures)

                    Chris
                  • Jenda Krynicky
                    - OK then. - Because then it s all backwards. - Why is that? - Please don t top-post! ... Declare the %bucket hash. It s not initialized to anything, but will
                    Message 9 of 15 , Sep 8, 2007
                    • 0 Attachment
                      - OK then.
                      - Because then it's all backwards.
                      - Why is that?
                      - Please don't top-post!


                      Ryan J Nauman <RJNauman@...> wrote:
                      > Ah, excellent. However, allow my noobness to kick in. Alright so you
                      > want me to create a hash that contains the entire list of words (values)
                      > associated with their alphabetized version (keys)? Should I do this as
                      > soon as I read in the input file? And should I continue with the line of
                      > code "my @WORDS = <INFILE>;" and create the bucket directly after?
                      >
                      > Now for the "dumping each bucket" portion I don't follow. Assuming I am
                      > following correctly on the first part, you're sorting the hash we made in
                      > the first step correct? I don't understand the print line. And is this
                      > used solely for sorting our newly created hash and then using my
                      > conditions against this new word list?
                      >
                      > Once the "bucket" hash is created would it be beneficial to my programs
                      > memory/execution time to close the INFILE and is there a way to delete the
                      > original @WORDS array now that the improved hash is in place?
                      >
                      > Thanks,
                      > Ryan

                      OK. Let me try to dissect the merlyn's code for you:

                      > merlyn@... wrote:
                      > Ooof, yeah. You're doing an exponential matching O(n squared)
                      > instead of just stashing everything according to its anagram.
                      >
                      > You need to use a "bucket" approach. As you compute each anagram,
                      > dump the original word into a bucket keyed by anagram, using a hash
                      > of arrayrefs...
                      >
                      > my %bucket;

                      Declare the %bucket hash. It's not initialized to anything, but will
                      be used as a HashOfArrays.

                      > for my $word (@words) {
                      > my $alphaword = alphabetize($word);

                      Let's sort the letters in the word

                      > push @{$bucket{$alphaword}}, $word;

                      And now let's the word at the the end of the array referenced by the
                      value of the hash %bucket using the key $alphaword.

                      When storing the first word containing a set of letters the
                      $bucket{$alphaword} doesn't exist in the hash, but that doesn't
                      matter. Perl will create it for us and as we are aparently expecting
                      the value to be a reference to an array ( @$ref is the array pointed
                      to by the reference stored in $ref) Perl even creates a brand new
                      array for us and stores its reference in $bucket{$alphaword}.

                      > }

                      Once this loop completes all words in the @words array have been
                      processed and are stored in the HashOfArrays named %bucket. They keys
                      are the sorted sets of letters and the values of the hash are
                      references to arrays containing the words.

                      You may clear the @words array now.

                      If your @words was created by
                      my @WORDS = <INFILE>;

                      You might actually get rid of the array completely and save memory.
                      Just remove that statement and change the loop to

                      while (my $word = <INFILE>) {
                      chomp($word);
                      my $alphaword = alphabetize($word);
                      push @{$bucket{$alphaword}}, $word;
                      }


                      > Now it's simply a matter of dumping each bucket:
                      >
                      > for my $alphaword (sort keys %bucket) {
                      > my $aref = $bucket{$alphaword};
                      > print "@$aref\n";
                      > }

                      As I said, %bucket is a hash of arrayrefs so in the loop above we get
                      the list of keys (the sorted sets of letters)
                      keys %bucket
                      sort it alphabetically
                      sort keys %bucket
                      and then loop through the sorted list, get the reference contained in
                      the hash and print the values in the referenced array.

                      HTH, Jenda

                      ===== Jenda@... === http://Jenda.Krynicky.cz =====
                      When it comes to wine, women and song, wizards are allowed
                      to get drunk and croon as much as they like.
                      -- Terry Pratchett in Sourcery
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