SOUNDEX.py

# -*- coding: utf-8 -*-


def SOUNDEX(TERM: str):

    # Step 0: Covert the TERM to UpperCase
    TERM = TERM.upper()
    TERM_LETTERS = [char for char in TERM if char.isalpha()]

    # List the Remove occurrences of A, E, I, O, U, Y, H, W.
    Remove_List = ("A", "E", "I", "O", "U", "Y", "H", "W")
    # Save the first letter
    first_letter = TERM_LETTERS[0]
    # Take the Other letters instead of First_Letter
    Characters = TERM_LETTERS[1:]
    # Remove items from Character using Remove_List
    Characters = [
        To_Characters
        for To_Characters in Characters
        if To_Characters not in Remove_List
    ]

    # if len(Characters) == 0:
    #    return first_letter + "000"

    # Replace all the Characters with Numeric Values (instead of the first letter) with digits according to Soundex Algorythem Ruels
    Replace_List = {
        ("B", "F", "P", "V"): 1,
        ("C", "G", "J", "K", "Q", "S", "X", "Z"): 2,
        ("D", "T"): 3,
        ("L"): 4,
        ("M", "N"): 5,
        ("R"): 6,
    }
    Characters = [
        value if char else char
        for char in Characters
        for group, value in Replace_List.items()
        if char in group
    ]

    # Step 3: Replace all adjacent same number with one number
    Characters = [
        char
        for Letter_Count, char in enumerate(Characters)
        if (
            Letter_Count == len(Characters) - 1
            or (
                Letter_Count + 1 < len(Characters)
                and char != Characters[Letter_Count + 1]
            )
        )
    ]

    # If the saved Characters’s Number is the same the resulting First Letter,keep the First Letter AND remove the Number
    if len(TERM_LETTERS) != 1:
        if first_letter == TERM_LETTERS[1]:
            Characters[0] = TERM[0]
        else:
            Characters.insert(0, first_letter)

    # If the Number of Characters are less than 4 insert 3 zeros to Characters
    # Remove all except first letter and 3 digits after it.
    # first_letter = Characters[0]
    # Characters = Characters[1:]

    # Characters = [char for char in Characters if isinstance(char, int)][0:3]
    while len(Characters) < 4:
        Characters.append(0)
    if len(Characters) > 4:
        Characters = Characters[0:4]

    INDEX = "".join([str(C) for C in Characters])
    return INDEX