Gunning Fog Index

import re

def count_words(text):
    """Counts the number of words in a text."""
    words = re.findall(r'\w+', text)
    return len(words)

def count_sentences(text):
    """Counts the number of sentences in a text."""
    sentences = re.split(r'[.!?]+', text)
    return len(sentences) - 1 if text[-1] in '.!?' else len(sentences)

def count_complex_words(text):
    """Counts the number of complex words in a text (words with three or more syllables)."""
    def syllable_count(word):
        word = word.lower()
        vowels = "aeiouy"
        count = 0
        if word[0] in vowels:
            count += 1
        for index in range(1, len(word)):
            if word[index] in vowels and word[index - 1] not in vowels:
                count += 1
        if word.endswith("e"):
            count -= 1
        if count == 0:
            count += 1
        return count

    words = re.findall(r'\w+', text)
    complex_words = [word for word in words if syllable_count(word) >= 3]
    return len(complex_words)

def gunning_fog_index(text):
    """Calculates the Gunning Fog Index for a given text."""
    num_words = count_words(text)
    num_sentences = count_sentences(text)
    num_complex_words = count_complex_words(text)

    if num_sentences == 0:
        return 0  # Avoid division by zero

    average_sentence_length = num_words / num_sentences
    percentage_complex_words = (num_complex_words / num_words) * 100

    fog_index = 0.4 * (average_sentence_length + percentage_complex_words)
    return fog_index

# Example usage
text = (
    "The Gunning Fog Index is a readability test for English writing. "
    "It estimates the years of formal education needed to understand the text on the first reading. "
    "Complex words are those with three or more syllables."
)

fog_index = gunning_fog_index(text)
print(f"The Gunning Fog Index for the given text is: {fog_index:.2f}")

OUTPUT

Gunning Fog Index Explanation

The Gunning Fog Index is a readability test that estimates the years of formal education needed to understand a text on the first reading. The implementation calculates the Gunning Fog Index using the following steps:

1. Words:
   • The code counts all words in the text using regular expressions.
2. Sentences:
   • Sentences are counted by splitting the text at sentence-ending punctuation marks, such as period (.), exclamation mark (!), and question mark (?).
3. Complex Words:
   • A complex word is defined as one with three or more syllables.
   • The syllable_count function estimates the number of syllables in a word by analyzing vowel patterns.
4. Gunning Fog Index Calculation:
   • The formula used for the Gunning Fog Index is:
     1. Average sentence length = number of words / number of sentences.
     2. Percentage of complex words = (number of complex words / number of words) * 100.
     3. The Gunning Fog Index is calculated as: 0.4 * (average sentence length + percentage of complex words).

Usage:

• A Gunning Fog Index of 7-8 is considered optimal for general readership.
• A higher score suggests that the text is more difficult to read, requiring higher levels of education.

This implementation provides a way to rank texts based on readability using the Gunning Fog Index, which is useful in various Natural Language Processing (NLP) applications such as document analysis, content creation, and education.

© Kevin Luzbetak