#!/usr/local/bin/perl -w =head1 NAME kocos.pl =head1 SYNOPSIS This program finds the Kth order co-occurrences of a given word. =head1 DESCRIPTION =head2 1. What are Kth order co-occurrences? Co-occurrences are the words which occur together in the same context. All words which co-occur with a given target word are called its co-occurrences. The concept of 2nd order co-occurrences is explained in the paper Automatic word Sense Discrimination [Schutze98]. According to this paper, the words which co-occur with the co-occurring words of a target word are called as the 2nd order co-occurrences of that word. So with each increasing order of co-occurrences, we introduce an extra level of indirection and find words co-occurring with the previous order co-occurrences. We generalize the concept of 2nd order co-occurrences from [Schutze98] to find the Kth order co-occurrences of a word. These are the words that co-occur with the (K-1)th order co-occurrences of a given target word. We have also found [Niwa&Nitta94] to be related to kocos. While we do not exactly reimplement the co-occurrence vectors they propose, we feel that kocos is at least similar in spirit. =head2 2. Usage Usage: kocos.pl [OPTIONS] BIGRAM =head2 3. Input =head3 3.1 BIGRAM Specify the BIGRAM file name on the command line after the program name and options (if any) as shown in the usage note. BIGRAM should be a bigram output(normal or extended) created by NSP programs - count.pl, statistic.pl or combig.pl. When count.pl and statistic.pl are run for creating bigrams (--ngram set to 2 or not specified), the programs list the bigrams of all words which co-occur together(in certain window). So we can say that if a bigram 'word1<>word2<>' is listed in the output of count.pl or statistic.pl program, it means that the words word1 and word2 are the co-occurrences of each other. In general you may want to consider the use of stop lists (--stop option in count.pl) to remove very common words such as "the" and "for", and also eliminate low frequency bigrams (--remove option in count.pl). The stop list is particularly important as high frequency words such as "the" or "for" will co-occur with many different words, and greatly expand the search needed to find kth order co-occurrences. If you want to run kocos.pl on a source file not created by either count or statistic program of this package, just make sure that each line of BIGRAM file will list two words WORD1 and WORD2 as WORD1<>WORD2<> The program minimally requires that there are exactly two words and they are separated by delimiter '<>' with an extra delimiter '<>' after the second word. So you may convert any non NSP input to this format where two words occurring in the same context are '<>' separated and provide it to kocos. Controlling scope of the context You may like to call two words as co-occurrences of each other if they occur within a specific distance from each other. We encourage in this case that you use --window w option of NSP program count.pl while creating a BIGRAM file. This will create bigrams of all words which co-occur within a distance w from each other. Thus --window w sets the maximum distance allowed between two words to call them co-occurrences of each other. Note that if the --window option is not used while creating BIGRAM input for kocos, only those words which come immediately next to each other will be considered as the co-occurrences (default window size being 2 for bigrams). =head2 4. Options =head3 4.1 --literal WORD With this option, the target WORD whose kth order co-occurrences are to be found can be directly specified on the command line. e.g. kocos.pl --literal line test.input will find the 1st order co-occurrences (by default) of the word 'line' using Bigrams listed in file test.input. kocos.pl --literal , --order 3 test.input will find 3rd order co-occurrences of ',' from file test.input. =head3 4.2 --regex REGEXFILE With this option, target word can be specified using Perl regular expression/s. The regex/s should be written in a file and multiple regex/s should either appear on separate lines or should be Perl 'OR' (|) separated. We provide this option to allow user to specify various morphological variants of the target word e.g. line, lines, Line,Lines etc. e.g. (1) let test.regex contains a regular expression for target word which is - /^[Ll]ines?$/ To use this for finding kocos, run kocos.pl with command kocos.pl --regex test.regex --order K test.input (2) To find say 2nd order co-occurrences of any general target word which occurs in Data in tags like Senseval Format, we use a regular expression /^\w+$/ in our regex file say test.regex and run kocos.pl using command kocos.pl --regex test.regex --order 2 eng-lex-sample.training.xml (3) To find 3rd order co-occurrences of any word that contains period '.' run kocos.pl using kocos.pl --literal . --order 3 test.input Or write a regex /\./ in file say test.regex and run kocos using kocos.pl --regex test.regex --order 3 test.input (4) To find 2nd order co-occurrences of all words that are numbers, write a regex like /^\d+$/ to a regexfile say test.regex and run kocos using, kocos.pl --regex test.regex --order 2 test.input Note: writing a regex /\d+/ will also match words like line20.1.cord, or art%10.fine456 that include numbers. Regex/s that should exactly match as target words should be delimited by ^ and $ as in /^[Ll]ines?$/. Specifying something like /[Ll]ines?/ will match with 'incline'. Note - The program kocos.pl requires that the target word is specified using either of the options --literal or --regex =head3 4.3 --order K If the value of K is specified using the command line option --order K, kocos.pl will find the Kth order co-occurrences of the target word. K can take any integer value greater than 0. If the value of K is not specified, the program will set K to 1 and will simply find the co-occurrences of the target (the word co-occurrence generally means first order co-occurrences). =head3 4.4 --trace TRACEFILE To see a detailed report of how each Kth order co-occurrence is reached as a sequence of K words, specify the name of a TRACEFILE on the command line using --trace TRACEFILE option. TRACEFILE will show the chains of K+1 words where the first word is the TARGET word and every ith word in the chain is a (i-1)th order co-occurrence of target which co-occurs with (i-1)th word in the chain. So a chain of K+1 words, TARGET->COC1->COC2->COC3....->COCK-1->COCK shows that COC1 is a first order co-occurrence of the TARGET. COC2 is a second order co-occurrence such that COC2 co-occurs with COC1 which in turn co-occurs with the TARGET. COC3 is a third order co-occurrence such that COC3 co-occurs with COC2 which in turn co-occurs with COC1 which co-occurs with TARGET. and so on...... =head3 4.6 --help This option will display the help message. =head3 4.7 --version This option will display version information of the program. =head2 5. Output The program will display a list of Kth order co-occurrences to standard output such that each co-occurrence occurs on a separate line and is followed by '<>' (just to be compatible with other programs in NSP). Note that the output of kocos.pl could be directly used by the program nsp2regex of the SenseTools Package (by Satanjeev Banerjee and Ted Pedersen) to convert Senseval data instances into feature vectors in ARFF format where our Kth order co-occurrences are used as features. For more information on SenseTools you can refer to its README: http://www.d.umn.edu/~tpederse/sensetools.html IMPORTANT NOTE If there are some kth order co-occurrences which are also the ith order co-occurrences (0 tags in the data file eng-lex-sample.training.xml, use a regular expression like /\w+/ from a file say test.regex, and run kocos.pl using kocos.pl --regex test.regex --order 2 test.input =head2 7. General Recommendations (a) Create a BIGRAM file using programs count.pl, statistic.pl or combig.pl of NSP Package. (b) Use --window W option of program count.pl to specify the scope of the context. Any word that occurs within a distance W from a target word will be treated as its co-occurrence. (c) Use either --literal or --regex option to specify the target word. We recommend use of regex support to detect forms of target word other than its base form. =head2 8. Examples of Kth order co-occurrences In all the following examples, we assume that the input comes from the file test.input and word 'line' is a target word. test.input => ---------------- print<>in<> | print<>line<> | text<>the<> | text<>line<> | file<>the<> | file<>in<> | line<>file | ---------------- (Note that test.input doesn't look like a valid count/statistic output because kocos.pl will minimally require two words WORD1 and WORD2 separated by '<>' with an extra '<>' after WORD2 as described in Section 3.1 of this README) (a) The 1st order co-occurrences of word 'line' can be found by running kocos.pl with either of the following commands - kocos.pl --literal line test.input OR kocos.pl --order 1 --literal line test.input This will display the co-occurrences of 'line' to standard output as shown below in the box. -------- text<> | file<> | print<>| -------- This is because the program finds the bigrams print<>line<> text<>line<> line<>file<> where word 'line' co-occurs with the words print, text and file which become the 1st order co-occurrences. (b) The 2nd order co-occurrences of word 'line' can be found by running kocos.pl with the following command - kocos.pl --literal line --order 2 test.input This will display the 2nd order co-occurrences of 'line' to standard output as shown below in the box. -------- the<> | in<> | -------- This is because the program finds the words print, text and file as the first order co-occurrences (as explained in case a) and finds bigrams print<>in<> text<>the<> file<>the<> file<>in where 'the' and 'in' co-occur with the words print, text, file. (c) To see how the 2nd order co-occurrences of word 'line' are reached run the program using the following command - kocos.pl --order 2 --trace test.trace test.input line This will display the 2nd order co-occurrences of 'line' to standard output as shown below in the box. -------- the<> | in<> | -------- and a detailed report of co-occurrence chains in test.trace file as shown in the box below. test.trace => ---------------- line->text->the| line->file->the| line->file->in | line->print->in| ---------------- where the first line shows that the word 'line' co-occurred with 'text' which co-occurred with 'the'. Hence 'the' became a 2nd order co-occurrence. Similarly, 'line' co-occurred with 'file' which in turn co-occurred with 'the' and 'in' which are therefore the 2nd order co-occurrences of 'line'. =head2 11. References [Niwa&Nitta94] Y. Niwa and Y. Nitta. Co-occurrence vectors from corpora vs. distance vectors from dictionaries. COLING-1994. [Schutze98] H. Schutze. Automatic word sense discrimination. Computational Linguistics,24(1):97-123,1998. =head1 AUTHORS Amruta Purandare, pura0010@umn.edu Ted Pedersen, tpederse@umn.edu Last updated on 12/05/2003 by TDP This work has been partially supported by a National Science Foundation Faculty Early CAREER Development award (#0092784). =head1 BUGS =head1 SEE ALSO http://www.d.umn.edu/~tpederse/nsp.html =head1 COPYRIGHT Copyright (C) 2002-2003, Amruta Purandare and Ted Pedersen This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to The Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. =cut ############################################################################### # Changelogs # Date Version By Changes Code # 03/30/2003 0.03 Amruta Regex support for ADP.03.1 # specifying target # word # # 07/02/2003 0.05 Amruta Redesigned algorithm ADP.05 # to improve performance # ############################################################################### # THE CODE STARTS HERE ############################################################################### # ================================ # COMMAND LINE OPTIONS AND USAGE # ================================ # show minimal usage message if no arguments if($#ARGV<0) { &showminimal(); exit; } # command line options use Getopt::Long; GetOptions ("help","version","order=i","trace=s","literal=s","regex=s"); # show help option if(defined $opt_help) { $opt_help=1; &showhelp(); exit; } # show version information if(defined $opt_version) { $opt_version=1; &showversion(); exit; } # if the order is specified if(defined $opt_order) { $order=$opt_order; } # otherwise set default to 1 else { $order=1; } # trace report will show how # a Kth order co-occurrence is # reached via a chain of # lower order co-occurrences if(defined $opt_trace) { $trace=$opt_trace; } # ---------------- # ADP.03.1 start # ---------------- # this part has been added during NSP version 0.55 release # target word is specified via --literal if(defined $opt_literal) { $target=$opt_literal; } # target specified as Perl regex/s in a file if(defined $opt_regex) { $regex_file=$opt_regex; if(!(-e $regex_file)) { print STDERR "ERROR($0): Regex file <$regex_file> doesn't exist.\n"; exit; } open(REG,$regex_file) || die "ERROR($0): Error(error code=$!) in opening Regex File <$regex_file>.\n"; undef $target; while() { chomp; s/^\s+//g; s/\s$//g; if(/^\s*$/) { next; } if(/^\//) { s/^\///; } else { print STDERR "ERROR($0): Regular Expression <$_> should start with '/'\n"; exit; } if(/\/$/) { s/\/$//; } else { print STDERR "ERROR($0): Regular Expression <$_> should end with '/'\n"; exit; } $target.="(".$_.")|"; } if(defined $target) { chop $target; } else { print "ERROR($0): No valid Perl regex found in Regex file <$regex_file>.\n"; exit; } } # -------------- # ADP.03.1 end # -------------- ############################################################################# # ================================ # INITIALIZATION AND INPUT # ================================ #$0 contains the program name along with #a complete path. Extract just the program #name and use in error messages $0=~s/.*\/(.+)/$1/; if(!defined $ARGV[0]) { print STDERR "ERROR($0): Please specify the SOURCE file name...\n"; exit; } #accept the input file name $infile=$ARGV[0]; #check if exists if(!-e $infile) { print STDERR "ERROR($0): Source file <$infile> doesn't exist...\n"; exit; } #open if exists open(IN,$infile) || die "Error($0): Error(code=$!) in opening <$infile> file.\n"; #check if the target word exists if(!defined $target) { print STDERR "ERROR($0): Please specify the target word using one of the --literal or --regex options.\n"; exit; } #check if order is valid if($order<1) { print STDERR "ERROR($0): Order should be greater than or equal to 1.\n"; exit; } #check if --trace is used if(defined $trace) { $ans="n"; #check if the TRACE_FILE already exists if(-e $trace) { print STDERR "WARNING($0): Trace file <$trace> already exists, overwrite(y/n)? "; $ans=; } if(!-e $trace || $ans=~/Y|y/) { #open the TRACE_FILE open(TRACE,">$trace") || die "Error($0): Error(code=$!) in opening Trace file <$trace>.\n"; } else { undef $trace; } } ############################################################################## # ============================= # Reading and Storing Bigrams # ============================= $line_num=0; #creating a coc_store data structure for storing all bigram strings from SOURCE #so that co-occurrences can be found looking at this data structure while($line=) { $line_num++; chomp $line; # handling blank lines if($line=~/^\s*$/) { next; } #store the bigram strings if($line=~/<>/) { #checking if the SOURCE is a valid NSP output for Bigrams $check_bigram=$line; $cnt=0; #count how many times <> occurs while($check_bigram=~/<>/) { $cnt++; $check_bigram=$'; } #should be 2 for bigrams if($cnt!=2) { print STDERR "ERROR($0): SOURCE file <$infile> is not a valid Bigram output of NSP at line <$line_num>.\n"; exit; } # store bigram in coc_store push @coc_store,$line; } } ############################################################################ # =========================================== # Ranking words according to their distance # From the target word # =========================================== # start with target word which # is at 0th level (rank) $rank{$target}=0; $word=$target; while($rank{$word}<$order) { # rank my co-occurrences &rank_cocs($word,$rank{$word}); # no more words in queue if($#words < 0) { if($rank{$word}<$order) { print "No co-occurrences at $order th level.\n"; } last; } else { # get the first word from queue $word=shift @words; } } ############################################################################# # ============================== # Printing Trace Report # ============================== # print trace report if(defined $trace) { # trace each kth order co-occurrence back foreach $word (@kocs) { # get all parents until the # target word is reached @chain=(); push @chain,$word; if(defined $regex_file) { while($word !~ /$target/) { push @chain,$parent{$word}; $word=$parent{$word}; } } else { while($word ne $target) { push @chain,$parent{$word}; $word=$parent{$word}; } } # print reverse chain @reversed=reverse @chain; print TRACE join("->",@reversed); print TRACE "\n"; } } ########################################################################### # ========================== # SUBROUTINE SECTION # ========================== #----------------------------------------------------------------------------- # ranks and queues the co-occurrences of a given word sub rank_cocs { my $word=$_[0]; # co-occurrences of given word # will be at rank(word)+1 my $level=$_[1]+1; #string from the coc_store my $coc_string=""; # check bigrams and rank words # co-occurring with the given # word foreach $coc_string (@coc_store) { @parts=split(/<>/,$coc_string); $word1=$parts[0]; $word2=$parts[1]; # current word is the target word # specified via regex option undef $got_coc; if($level==1 && defined $regex_file) { # if exactly one of the words matches # the target, extract the other if($word1=~/$word/ && !defined $rank{$word2} && $word2!~/$target/) { $got_coc=$word2; $parent=$word1; } elsif($word2=~/$word/ && !defined $rank{$word1} && $word1!~/$target/) { $got_coc=$word1; $parent=$word2; } } elsif(defined $regex_file) { # if one of the words matches the # given word and other doesn't match # the target word if($word1 eq $word && !defined $rank{$word2} && $word2!~/$target/) { $got_coc=$word2; $parent=$word1; } elsif($word2 eq $word && !defined $rank{$word1} && $word1!~/$target/) { $got_coc=$word1; $parent=$word2; } } else { # one of the words matches the # given word if($word1 eq $word && !defined $rank{$word2}) { $got_coc=$word2; $parent=$word1; } elsif($word2 eq $word && !defined $rank{$word1}) { $got_coc=$word1; $parent=$word2; } } if(defined $got_coc) { # rank the obtained coc $rank{$got_coc}=$level; # queue the coc push @words,$got_coc; # print if level is K if($level==$order) { print "$got_coc<>\n"; } # store link to parent for tracing if(defined $trace) { $parent{$got_coc}=$parent; if($level==$order) { push @kocs,$got_coc; } } } } } #----------------------------------------------------------------------------- #show minimal usage message sub showminimal() { print "Usage: kocos.pl [OPTIONS] BIGRAM"; print "\nTYPE kocos.pl --help for help\n"; } #----------------------------------------------------------------------------- #show help sub showhelp() { print "Usage: kocos.pl [OPTIONS] BIGRAM Displays the kth order Co-occurrences of a given target word. Target word should be specified via --literal or --regex option. BIGRAM A list of bigrams formatted like the output (extended or normal) of NSP programs count.pl or statistic.pl. OPTIONS: --literal LITERAL Specify the target word directly on command line as a literal. --regex REGEXFILE Specify a file containing Perl regular expression/s that define the target word. --order K Specify the value of K (K>0) to find the kth order co-occurrences. A Kth order co-occurrence is a word that co-occurs with a (K-1)th order co-occurrence of the target word. By default, the value of K is set to 1 which simply lists the words that co-occur with a given target word. When K is 2, all words that co-occur with the words that co-occur with the target word are shown, and so on for higher orders. --trace TRACEFILE Specify the name of a TRACEFILE to see a detailed trace report showing the chains of co-occurrences. A chain shows how a Kth order co-occurrence is reached as a sequence of K lower order co-occurrences. e.g. WORD->First->Second->Third..->Kth shows that 'First' is a first order co-occurrence of WORD, 'Second' is a second order co-occurrence of WORD which co-occurs with 'First'. 'Third' is a third order co-occurrence of WORD which co-occurs with 'Second' and so on until K is reached. --help To display this message. --version To display the version information.\n"; } #------------------------------------------------------------------------------ #version information sub showversion() { print "kocos.pl - version 0.05\n"; print "Copyright (C) 2002-2003, Amruta Purandare & Ted Pedersen\n"; print "Date of Last Update: 07/01/2003\n"; } ############################################################################# =head1 AUTHORS Amruta Purandare, University of Minnesota, Duluth, pura0010@d.umn.edu Ted Pedersen, University of Minnesota, Duluth, tpederse@umn.edu =head1 BUGS =head1 SEE ALSO http://www.d.umn.edu/~tpederse/nsp.html =head1 COPYRIGHT Copyright (C) 2002-2003, Amruta Purandare & Ted Pedersen This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to The Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. =cut