=head1 NAME Lingua::EN::Fathom - Measure readability of English text =head1 SYNOPSIS use Lingua::EN::Fathom; my $text = Lingua::EN::Fathom->new(); # Analyse contents of a text file $text->analyse_file("sample.txt"); # Analyse contents of a text file $accumulate = 1; # Analyse contents of a text string $text->analyse_block($text_string,$accumulate); # TO Do, remove repetition $num_chars = $text->num_chars; $num_words = $text->num_words; $percent_complex_words = $text->percent_complex_words; $num_sentences = $text->num_sentences; $num_text_lines = $text->num_text_lines; $num_blank_lines = $text->num_blank_lines; $num_paragraphs = $text->num_paragraphs; $syllables_per_word = $text->syllables_per_word; $words_per_sentence = $text->words_per_sentence; # comment needed %words = $text->unique_words; foreach $word ( sort keys %words ) { print("$words{$word} :$word\n"); } $fog = $text->fog; $flesch = $text->flesch; $kincaid = $text->kincaid; print($text->report); =head1 REQUIRES Perl, version 5.001 or higher, Lingua::EN::Syllable =head1 DESCRIPTION This module analyses English text in either a string or file. Totals are then calculated for the number of characters, words, sentences, blank and non blank (text) lines and paragraphs. Three common readability statistics are also derived, the Fog, Flesch and Kincaid indices. All of these properties can be accessed through individual methods, or by generating a text report. A hash of all unique words and the number of times they occur is generated. =head1 METHODS =head2 new The C method creates an instance of an text object This must be called before any of the following methods are invoked. Note that the object only needs to be created once, and can be reused with new input data. my $text = Lingua::EN::Fathom->new(); =head2 analyse_file The C method takes as input the name of a text file. Various text based statistics are calculated for the file. This method and C are prerequisites for all the following methods. An optional argument may be supplied to control accumulation of statistics. If set to a non zero value, all statistics are accumulated with each successive call. $text->analyse_file("sample.txt"); =head2 analyse_block The C method takes as input a text string. Various text based statistics are calculated for the file. This method and C are prerequisites for all the following methods. An optional argument may be supplied to control accumulation of statistics. If set to a non zero value, all statistics are accumulated with each successive call. $text->analyse_block($text_str); =head2 num_chars Returns the number of characters in the analysed text file or block. This includes characters such as spaces, and punctuation marks. =head2 num_words Returns the number of words in the analysed text file or block. A word must consist of letters a-z with at least one vowel sound, and optionally an apostrophe or hyphen. Items such as "&, K108, NW" are not counted as words. =head2 percent_complex_words Returns the percentage of complex words in the analysed text file or block. A complex word must consist of three or more syllables. This statistic is used to calculate the fog index. =head2 num_sentences Returns the number of sentences in the analysed text file or block. A sentence is any group of words and non words terminated with a single full stop. Spaces may occur before and after the full stop. =head2 num_text_lines Returns the number of lines containing some text in the analysed text file or block. =head2 num_blank_lines Returns the number of lines NOT containing any text in the analysed text file or block. =head2 num_paragraphs Returns the number of paragraphs in the analysed text file or block. =head2 syllables_per_word Returns the average number of syllables per word in the analysed text file or block. =head2 words_per_sentence Returns the average number of words per sentence in the analysed text file or block. =head2 READABILITY Three indices of text readability are calculated. They all measure complexity as a function of syllables per word and words per sentence. They assume the text is well formed and logical. You could analyse a passage of nonsensical English and find the readability is quite good, provided the words are not too complex and the sentences not too long. For more information see: L =head2 fog Returns the Fog index for the analysed text file or block. ( words_per_sentence + percent_complex_words ) * 0.4 The Fog index, developed by Robert Gunning, is a well known and simple formula for measuring readability. The index indicates the number of years of formal education a reader of average intelligence would need to read the text once and understand that piece of writing with its word sentence workload. 18 unreadable 14 difficult 12 ideal 10 acceptable 8 childish =head2 flesch Returns the Flesch reading ease score for the analysed text file or block. 206.835 - (1.015 * words_per_sentence) - (84.6 * syllables_per_word) This score rates text on a 100 point scale. The higher the score, the easier it is to understand the text. A score of 60 to 70 is considered to be optimal. =head2 kincaid Returns the Flesch-Kincaid grade level score for the analysed text file or block. (11.8 * syllables_per_word) + (0.39 * words_per_sentence) - 15.59; This score rates text on U.S. grade school level. So a score of 8.0 means that the document can be understood by an eighth grader. A score of 7.0 to 8.0 is considered to be optimal. =head2 unique_words Returns a hash of unique words. The words (in lower case) are held in the hash keys while the number of occurrences are held in the hash values. =head2 report print($text->report); Produces a text based report containing all Fathom statistics for the currently analysed text block or file. For example: Number of characters : 813 Number of words : 135 Percent of complex words : 20.00 Average syllables per word : 1.7704 Number of sentences : 12 Average words per sentence : 11.2500 Number of text lines : 13 Number of blank lines : 8 Number of paragraphs : 4 READABILITY INDICES Fog : 12.5000 Flesch : 45.6429 Flesch-Kincaid : 9.6879 The return value is a string containing the report contents =head1 SEE ALSO L,L,L =head1 POSSIBLE EXTENSIONS Count white space and punctuation characters Allow user control over what strictly defines a word =head1 LIMITATIONS The syllable count provided in Lingua::EN::Syllable is about 90% accurate Acronyms that contain vowels, like GPO, will be counted as words. The fog index should exclude proper names =head1 BUGS None known =head1 AUTHOR Lingua::EN::Fathom was written by Kim Ryan . =head1 COPYRIGHT AND LICENSE Copyright (c) 2018 Kim Ryan. All rights reserved. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. =cut #------------------------------------------------------------------------------ package Lingua::EN::Fathom; use Lingua::EN::Syllable; use Lingua::EN::Sentence; use strict; use warnings; our $VERSION = '1.22'; #------------------------------------------------------------------------------ # Create a new instance of a text object. sub new { my $class = shift; my $text = {}; bless($text,$class); return($text); } #------------------------------------------------------------------------------ # Analyse text stored in a file, reading from the file one line at a time sub analyse_file { my $text = shift; my ($file_name,$accumulate) = @_; unless ( $accumulate ) { $text = &_initialize($text); } $text->{file_name} = $file_name; # Only analyse non-empty text files unless ( -T $file_name and -s $file_name ) { return($text); } open(IN_FH,"<$file_name"); my $in_paragraph = 0; my $all_text; while ( ) { my $one_line = $_; $all_text .= $one_line; ($in_paragraph,$text) = &_analyse_line($text,$one_line,$in_paragraph); } close(IN_FH); my $sentences= Lingua::EN::Sentence::get_sentences($all_text); $text->{num_sentences} = scalar(@$sentences); $text->_calculate_readability; return($text); } #------------------------------------------------------------------------------ # Analyse a block of text, stored as a string. The string may contain line # terminators. sub analyse_block { my $text = shift; my ($block,$accumulate) = @_; unless ( $accumulate ) { $text = &_initialize($text); } unless ( $block ) { return($text); } my $in_paragraph = 0; # by setting split limit to -1, we prevent split from stripping # trailing line terminators my @all_lines = split(/\n/,$block,-1); my $one_line; foreach $one_line ( @all_lines ) { ($in_paragraph,$text) = &_analyse_line($text,$one_line,$in_paragraph); } my $sentences= Lingua::EN::Sentence::get_sentences($block); $text->{num_sentences} = scalar(@$sentences); $text->_calculate_readability; return($text); } #------------------------------------------------------------------------------ sub num_chars { my $text = shift; return($text->{num_chars}); } #------------------------------------------------------------------------------ sub num_words { my $text = shift; return($text->{num_words}); } #------------------------------------------------------------------------------ sub percent_complex_words { my $text = shift; return($text->{percent_complex_words}); } #------------------------------------------------------------------------------ sub num_sentences { my $text = shift; return($text->{num_sentences}); } #------------------------------------------------------------------------------ sub num_text_lines { my $text = shift; return($text->{num_text_lines}); } #------------------------------------------------------------------------------ sub num_blank_lines { my $text = shift; return($text->{num_blank_lines}); } #------------------------------------------------------------------------------ sub num_paragraphs { my $text = shift; return($text->{num_paragraphs}); } #------------------------------------------------------------------------------ sub syllables_per_word { my $text = shift; return($text->{syllables_per_word}); } #------------------------------------------------------------------------------ sub words_per_sentence { my $text = shift; return($text->{words_per_sentence}); } #------------------------------------------------------------------------------ sub fog { my $text = shift; return($text->{fog}); } #------------------------------------------------------------------------------ sub flesch { my $text = shift; return($text->{flesch}); } #------------------------------------------------------------------------------ sub kincaid { my $text = shift; return($text->{kincaid}); } #------------------------------------------------------------------------------ # Return anonymous hash of all the unique words in analysed text. The words # occurrence count is stored in the hash value. sub unique_words { my $text = shift; if ( $text->{unique_words} ) { return( %{ $text->{unique_words} } ); } else { return(undef); } } #------------------------------------------------------------------------------ # Provide a formatted text report of all statistics for a text object. # Return report as a string. sub report { my $text = shift; my $report = ''; $text->{file_name} and $report .= sprintf("File name : %s\n",$text->{file_name} ); $report .= sprintf("Number of characters : %d\n", $text->num_chars); $report .= sprintf("Number of words : %d\n", $text->num_words); $report .= sprintf("Percent of complex words : %.2f\n",$text->percent_complex_words); $report .= sprintf("Average syllables per word : %.4f\n",$text->syllables_per_word); $report .= sprintf("Number of sentences : %d\n", $text->num_sentences); $report .= sprintf("Average words per sentence : %.4f\n",$text->words_per_sentence); $report .= sprintf("Number of text lines : %d\n", $text->num_text_lines); $report .= sprintf("Number of blank lines : %d\n", $text->num_blank_lines); $report .= sprintf("Number of paragraphs : %d\n", $text->num_paragraphs); $report .= "\n\nREADABILITY INDICES\n\n"; $report .= sprintf("Fog : %.4f\n",$text->fog); $report .= sprintf("Flesch : %.4f\n",$text->flesch); $report .= sprintf("Flesch-Kincaid : %.4f\n",$text->kincaid); return($report); } #------------------------------------------------------------------------------ # PRIVATE METHODS #------------------------------------------------------------------------------ sub _initialize { my $text = shift; $text->{num_chars} = 0; $text->{num_syllables} = 0; $text->{num_words} = 0; $text->{num_complex_words} = 0; $text->{num_text_lines} = 0; $text->{num_blank_lines} = 0; $text->{num_paragraphs} = 0; $text->{num_sentences} = 0; $text->{unique_words} = (); $text->{file_name} = ''; $text->{fog} = 0; $text->{flesch} = 0; $text->{kincaid} = 0; return($text); } #------------------------------------------------------------------------------ # Increment number of text lines, blank lines and paragraphs sub _analyse_line { my $text = shift; my ($one_line,$in_paragraph) = @_; if ( $one_line =~ /\w/ ) { chomp($one_line); $text = &_analyse_words($text,$one_line); $text->{num_text_lines}++; unless ( $in_paragraph ) { $text->{num_paragraphs}++; $in_paragraph = 1; } } else # empty or blank line { $text->{num_blank_lines}++; $in_paragraph = 0; } return($in_paragraph,$text); } #------------------------------------------------------------------------------ # Try to detect real words in line. Increment syllable, word, and complex word counters. sub _analyse_words { my $text = shift; my ($one_line) = @_; $text->{num_chars} += length($one_line); # Word found, such as: twice, BOTH, a, I'd, non-plussed .. # Ignore words like 'Mr.', K12, &, X.Y.Z ... # It could be argued that Mr. is a word, but this approach should detect most of the non words # whivh have punctuation or numbers in them while ( $one_line =~ /\b([a-z][-'a-z]*)\b/ig ) { my $one_word = $1; # Try to filter out acronyms and abbreviations by accepting # words with a vowel sound. This won't work for GPO etc. next unless $one_word =~ /[aeiouy]/i; # Test for valid hyphenated word like be-bop if ( $one_word =~ /-/ ) { next unless $one_word =~ /[a-z]{2,}-[a-z]{2,}/i; } # word frequency count $text->{unique_words}{lc($one_word)}++; $text->{num_words}++; # Use subroutine from Lingua::EN::Syllable my $num_syllables_current_word = syllable($one_word); $text->{num_syllables} += $num_syllables_current_word; # Required for Fog index, count non hyphenated words of 3 or more # syllables. Should add check for proper names in here as well if ( $num_syllables_current_word > 2 and $one_word !~ /-/ ) { $text->{num_complex_words}++; } } ## Remove full stops to denote common abbreviations. By requiring a following space ## we know the '.' is not also ending the sentence. # ## People's titles #$one_line =~ s/Mr\. /Mr /ig; #$one_line =~ s/Mrs\. /Mrs /ig; #$one_line =~ s/Ms\. /Ms /ig; #$one_line =~ s/M\/s\. /M\/s /ig; #$one_line =~ s/Dr\. /Dr /ig; #$one_line =~ s/Prof\. /Prof /ig; #$one_line =~ s/Det\. /Det /ig; #$one_line =~ s/Insp\. /Insp /ig; # ## Commercial abbreviations #$one_line =~ s/Pty\. /Pty /ig; #$one_line =~ s/PLC\. /PLC /ig; #$one_line =~ s/Ltd\. /Ltd /ig; #$one_line =~ s/Inc\. /Inc /ig; # ## Other abbreviations #$one_line =~ s/etc\. /etc /ig; #$one_line =~ s/vs\. /vs /ig; # # ## Remove quotation marks as a quote followed by a full stop will not be ## correctly detected by the following regexps. #$one_line =~ s/"//g; #$one_line =~ s/'//g; # Now search for '.', '?' or '!' at the end of the normalised sentence. # while ( $one_line =~ /\b\s*[.!?]\s*\b/g ) { $text->{num_sentences}++ } # Check for final sentence, with no following words. # $one_line =~ /\b\s*[.!?]\s*$/g and $text->{num_sentences}++; return($text); } #------------------------------------------------------------------------------ # Determine the three readability indices sub _calculate_readability { my $text = shift; if ( $text->{num_sentences} and $text->{num_words} ) { $text->{words_per_sentence} = $text->{num_words} / $text->{num_sentences}; $text->{syllables_per_word} = $text->{num_syllables} / $text->{num_words}; $text->{percent_complex_words} = ( $text->{num_complex_words} / $text->{num_words} ) * 100; $text->{fog} = ( $text->{words_per_sentence} + $text->{percent_complex_words} ) * 0.4; $text->{flesch} = 206.835 - (1.015 * $text->{words_per_sentence}) - (84.6 * $text->{syllables_per_word}); $text->{kincaid} = (11.8 * $text->{syllables_per_word}) + (0.39 * $text->{words_per_sentence}) - 15.59; } else { $text->{words_per_sentence} = 0; $text->{syllables_per_word} = 0; $text->{fog} = 0; $text->{flesch} = 0; $text->{kincaid} = 0; } } #------------------------------------------------------------------------------ return(1);