NAME

Lingua::EN::Fathom - Measure readability of English text

SYNOPSIS

use Lingua::EN::Fathom;

my $sample =
q{Determine the readability of the given text file or block. Words
need to contain letters, and optionally numbers (such as Gr8). There
is no understanding of context.

Numbers like 1.234 are valid, but strings like #### are ignored.};

my $f = Fathom.new();
$f.analyse_block($sample,0);
say $f.report;

#`[
Output is:
Number of characters       : 227
Number of words            : 37
Percent of complex words   : 13.51
Average syllables per word : 1.5676
Number of sentences        : 4
Average words per sentence : 9.2500
Number of text lines       : 4
Number of blank lines      : 1
Number of paragraphs       : 2
]

READABILITY INDICES

Fog                        : 9.1054s
Flesch                     : 64.8300
Flesch-Kincaid             : 6.5148

# Access individual statistics
say $f.percent_complex_words;  # 13.51

# Analyse file contents, accumualting statisitics over succesive calls
my $accumulate = 1;
$f.analyse_file('sample.txt',$accumulate);

REQUIRES

Lingua::EN::Syllable, Lingua::EN::Sentence

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 method attributed, or by generating a text report.

METHODS

new

The new method creates an instance of an Fathom 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 $f = Fathom.new();

analyse_file

The analyse_file method takes as input the name of a text file. Various text based statistics are calculated for the file. This method and analyse_block 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.

$f.analyse_file('sample.txt',$accumulate);

analyse_block

The analyse_block method takes as input a text string. Various text based statistics are calculated for the file. This method or analyse_file is a 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.

$f.analyse_block($sample,0);

head2 report

say $f.report;

Produces a text based report containing all Fathom statistics for the currently analysed text block or file. Shopuld only be called after a call to analyse_block or analyse_file, The return value is a string containing the report contents

attributes

Accessed the individual readability statistics say $f.num_words;

The attributes are

$.num_sents;
    $.num_text_lines;
    $.num_blank_lines;
    $.num_paragraphs;    
    $.num_chars;
    $.num_syllables;
    $.num_complex_words;
    $.words_per_sentence;
    $.syllables_per_word ;
    $.percent_complex_words;    

$.fog;
    $.flesch;
    $.kincaid;    

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: https://en.wikipedia.org/wiki/Readability

fog

( 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

flesch

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.

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.

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.

SEE ALSO

Lingua::EN::Syllable,Lingua::EN::Sentence,

LIMITATIONS

The syllable count provided in Lingua::EN::Syllable is about 90% accurate The fog index should exclude proper names

AUTHOR

Lingua::EN::Fathom was written by Kim Ryan <kimryan at cpan dot org>.

COPYRIGHT AND LICENSE

Copyright (c) 2023 Kim Ryan. All rights reserved.

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.