count_words_in_string.py

################################################################################
#
# Program: Count The Words In A String
# 
# Description: Program to count the words in a string using Python.
#
# YouTube Lesson: https://www.youtube.com/watch?v=iB_Y295lT9I
#
# Author: Kevin Browne @ https://portfoliocourses.com
#
################################################################################

import string

# Return the count of the words in the string text
def count_words(text):
    
    # Filters out all punctuation marks in the original string.  The translate()
    # method will take text and return a new string created using the
    # translation table created by str.maketrans().  The str.maketrans() method
    # could be used to replace characters with other characters in the string 
    # but we pass in empty strings as the first two arguments as we aren't going
    # to do this.  We do pass in string.punctuation as the third argument, a 
    # string constant contained in the string module containing all punctuation
    # mark characters.  This optional third argument will have all the characters
    # of this string (string.punctuation) removed from text.
    #
    # We remove these punctuation marks because we don't want something like a 
    # dash character '-' to be considered a word.
    #
    after = text.translate(str.maketrans('','',string.punctuation))

    # We split the string wherever there are whitespace characters like ' ', 
    # '\n' and '\t' using after.split() which will give us a list of string 
    # items like: ['9', 'words', 'separated', ... and on ... ].  We don't want 
    # numbers like '9' to be considered a word.  So we take this list and use
    # it in a list comprehension, where we produce a new list containing only
    # the original list items that are ONLY made up of alphabetic characters.
    # The isalpha() string method will only return true if the string is only
    # made up of alphabetic characters, and so we use this to do the filtering.
    #
    words = [word for word in after.split() if word.isalpha()]
 
    # Find the number of items in the list using len(), i.e. number of words
    # in the string
    total_words = len(words)
    
    # Return the word count
    return total_words

# Test string.  Notably we don't want to consider '9' and '-' to be words, so 
# our function is built to remove punctuation marks from the string, and to 
# NOT consider portions of the string in-between whitespace characters to be 
# words IF they contain non-alphabetic characters.
example = "9 words separated by spaces - but dashes are not words"

# Output the word count
print(count_words(example))