"""Detect English Module
Provides functions to determine whether a given string is in the English language.
Attributes:
UPPERLETTERS (str): String containing all latin-based letters in uppercase.
LETTERS_AND_SPACE (str): String containing upper and lowercase letters as well as space, newline, and tab.
DICTIONARY_FILE (str): String containing absolute path of dictionary.txt file.
ENGLISH_WORDS (dict): Dictionary containing all words from dictionary.txt as keys.
Example:
>>> import pythontutorials.books.CrackingCodesWithPython.Chapter11.detectEnglish as detectEnglish
>>> someString = 'Enthusiasm is contagious. Not having enthusiasm is also contagious.'
>>> detectEnglish.isEnglish(someString) # Returns True or False
True
Note:
* https://www.nostarch.com/crackingcodes/ (BSD Licensed)
* There must be a "dictionary.txt" file in this directory with all
English words in it, one word per line. You can download this from
https://www.nostarch.com/crackingcodes/.
"""
UPPERLETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
LETTERS_AND_SPACE = UPPERLETTERS + UPPERLETTERS.lower() + ' \t\n'
DICTIONARY_FILE = '/home/jose/PycharmProjects/python-tutorials/pythontutorials/books/CrackingCodesWithPython/Chapter11/dictionary.txt'
[docs]def loadDictionary() -> dict:
"""Load dictionary file
Loads dictionary.txt file and creates a dictionary with all words as keys.
Returns:
Dictionary with all words in dictionary.txt as keys.
"""
dictionaryFile = open(DICTIONARY_FILE)
englishWords = {}
for word in dictionaryFile.read().split('\n'):
englishWords[word] = None
dictionaryFile.close()
return englishWords
ENGLISH_WORDS = loadDictionary()
[docs]def getEnglishCount(message: str) -> float:
"""Get count of English words
For given message, counts number of words in English
dictionary and returns ratio of English words out of total words.
Args:
message: String with message to check for English words.
Returns:
Ratio of number of English words / total number of words.
"""
message = message.upper()
message = removeNonLetters(message)
possibleWords = message.split()
if not possibleWords: # Given [] = False, if possibleWords = [] then if not possibleWords = True
return 0.0 # No words at all, so return 0.0
matches = 0
for word in possibleWords:
if word in ENGLISH_WORDS:
matches += 1
return float(matches) / len(possibleWords)
[docs]def removeNonLetters(message: str) -> str:
"""Removes non-letters
Removes non-letter characters from given message.
Args:
message: String with message to remove non-letter characters from.
Returns:
New string with non-letter characters removed.
"""
lettersOnly = []
for symbol in message:
if symbol in LETTERS_AND_SPACE:
lettersOnly.append(symbol)
return ''.join(lettersOnly)
[docs]def isEnglish(message: str, wordPercentage: int=20, letterPercentage: int=85) -> bool:
"""Determines whether message is English
Using given word percentage and letter percentage, determines if a given message is in the English language.
Args:
message: String containing message to determine if it is English.
wordPercentage: Integer representing percentage of words in message that must be English.
letterPercentage: Integer representing percentage of characters in message that must be letters or spaces.
Returns:
True if message is in English language, False otherwise.
Note:
* By default, 20% of the words must exist in the dictionary file, and
85% of all the characters in the message must be letters or spaces
(not punctuation or numbers).
"""
wordsMatch = getEnglishCount(message) * 100 >= wordPercentage
numLetters = len(removeNonLetters(message))
messageLettersPercentage = float(numLetters) / len(message) * 100
lettersMatch = messageLettersPercentage >= letterPercentage
return wordsMatch and lettersMatch