Pig Latin

piglatin.py

Please type a word: hello
ellohay
Please type a word: goodbye
oodbyegay
Please type a word: control-d or control-z enter to signal end of input

Things to try

What happens if the user presses return or enter without typing a word?

Please type a word:
Traceback (most recent call last):
  File "/Users/myname/python/subscript.py", line 20, in <module>
    firstCharacter = word[0]
IndexError: string index out of range

while True:

    try:
        word = input("Please type a word: ")
    except EOFError:
        sys.exit(0)

    if len(word) == 0:   #or if not word:
        firstCharacter = ""
        rest = ""
    else:
        firstCharacter = word[0]
        rest = word[1:]

    pigLatin = rest + firstCharacter + "ay"
    print(pigLatin)

Please type a word: return or enter
ay
Please type a word: b
bay
Please type a word: control-d or control-z

If the input word starts with a vowel, do not chop off the first letter and move it to the end. Instead, simply append “way”. A “y” at the start of a word is almost always a consonant. (The only exception I can think of is Ypsilanti, Michigan.) For the continuation character \, see Explicit line joining.

while True:

    try:
        word = input("Please type a word: ")
    except EOFError:
        sys.exit(0)

    if not word:
        leadingConsonant = ""
        rest = ""
    else:
        #If the word starts with a vowel, temporarily prefix "w" to the word.
        if word[0] == "a" or word[0] == "e" or word[0] == "i" or word[0] == "o" \
            or word[0] == "u":
            word = "w" + word
        leadingConsonant = word[0]
        rest = word[1:]

    pigLatin = rest + leadingConsonant + "ay"
    print(pigLatin)

Please type a word: apple
appleway
Please type a word: banana
ananabay
Please type a word: etc.

Change

        #If the word starts with a vowel, temporarily prefix "w" to the word.
        if word[0] == "a" or word[0] == "e" or word[0] == "i" or word[0] == "o" \
            or word[0] == "u":
            word = "w" + word

        #If the word starts with a vowel, temporarily prefix "w" to the word.
        if word[0] in "aeiou":
            word = "w" + word

Please type a word: apple
appleway
Please type a word: banana
ananabay
Please type a word: etc.

If the input word begins with any group of one or more consecutive consonants, chop off the whole group and move it to the end. (A “y” among the leading consonants is almost always a vowel: cryptography, psychological, symbol, synthetic.)

The yellow section uses the LBYL style (rather than EAFP) to check if the end of the string has been reached before we attempt to use the [ ]. Why does this section use while instead of for? Well, suppose the word was CBS. In this case, the yellow code should set i to 3. But the loop for i in range(len(word)): could set i no higher than 2.

while True:

    try:
        word = input("Please type a word: ")
    except EOFError:
        sys.exit(0)

    if not word:
        leadingConsonants = ""
        rest = ""
    else:
        #If the word starts with a vowel, temporarily prefix "w" to the word.
        if word[0] in "aeiou":
            word = "w" + word

        i = 0
        while i < len(word) and word[i] in "bcdfghjklmnpqrstvwxz":
            i += 1

        #At this point, i is the number of leading consonants in the word.
        leadingConsonants = word[:i]   #the first i characters
        rest = word[i:]                #the rest of the word

    pigLatin = rest + leadingConsonants + "ay"
    print(pigLatin)

Please type a word: rump
umpray
Please type a word: trump
umptray
Please type a word: string
ingstray
Please type a word: schmuck
uckschmay

Another way to find the number of leading consonants in the word:

import re   #regular expressions

        m = re.match(r"^([bcdfghjklmnpqrstvwxz]*)", word)   #m is a Match.
        i = len(m.group(1))

The output word should be capitalized if and only if the input word was. The value of the expression
word[0].isupper()
is either True or False.

while True:

    try:
        word = input("Please type a word: ")
    except EOFError:
        sys.exit(0)

    if not word:
        capitalize = False
        leadingConsonants = ""
        rest = ""
    else:
        capitalize = word[0].isupper()   #Make a mental note.
        word = word.lower()

        #If the word starts with a vowel, temporarily prefix "w" to the word.
        if word[0] in "aeiou":
            word = "w" + word

        i = 0
        while i < len(word) and word[i] in "bcdfghjklmnpqrstvwxz":
            i += 1

        #At this point, i is the number of leading consonants in the word.
        leadingConsonants = word[:i]   #the first i characters
        rest = word[i:]                #the rest of the word

    pigLatin = rest + leadingConsonants + "ay"
    if capitalize:
        pigLatin = pigLatin.capitalize()
    print(pigLatin)

Please type a word: trump
umptray
Please type a word: Trump
Umptray

Let the user input an entire sentence. Assume each word is a group of one or more consecutive letters. Between each word is a group of one or more consecutive non-letters. There may also be a group of non-letters at the beginning and end of the line.

The yellow sections use the LBYL style (rather than EAFP) to check if the end of the string has been reached.

while True:

    try:
        sentence = input("Please type a sentence: ")
    except EOFError:
        sys.exit(0)

    while sentence:   #or while len(sentence) > 0:
        i = 0
        while i < len(sentence) and not sentence[i].isalpha():
            i += 1

        #At this point, i is the number of leading non-letters
	#(spaces, punctuation marks, etc).
        leadingNonletters = sentence[:i]
        sentence = sentence[i:]   #Remove the leading non-letters.
        print(leadingNonletters, end = "")

        if not sentence:
            #nothing left to translate
            break

        i = 0
        while i < len(sentence) and sentence[i].isalpha():
            i += 1

        #At this point, i is the number of leading letters in the sentence.
        word = sentence[:i]     #the leftmost surviving word in the sentence
        sentence = sentence[i:] #Remove the leading word.

        if not word:
            capitalize = False
            leadingConsonants = ""
            rest = ""
        else:
            capitalize = word[0].isupper()
            word = word.lower()

            #If the word starts with a vowel, temporarily prefix "w" to the word.
            if word[0] in "aeiou":
                word = "w" + word

            i = 0
            while i < len(word) and word[i] in "bcdfghjklmnpqrstvwxz":
                i += 1

            #At this point, i is the number of leading consonants in the word.
            leadingConsonants = word[:i]   #the first i characters
            rest = word[i:]                #the rest of the word

        pigLatinWord = rest + leadingConsonants + "ay"
        if capitalize:
            pigLatinWord = pigLatinWord.capitalize()
        print(pigLatinWord, end = "")   #Output a word translated into Pig Latin.

    print()   #Output a newline at the end of the translated sentence.

Please type a sentence: Read my lips: "No new taxes!"
Eadray ymay ipslay: "Onay ewnay axestay!"

The while loop would be easier to read if we took the code that translates one word into Pig Latin and packaged it separately as a user-defined function.

def pigLatin(word):
    """
    Return the Pig Latin translation of the word.
    """
    assert isinstance(word, str)

    if not word:
        capitalize = False
        leadingConsonants = ""
        rest = ""
    else:
        capitalize = word[0].isupper()
        word = word.lower()

        #If the word starts with a vowel, temporarily prefix "w" to the word.
        if word[0] in "aeiou":
            word = "w" + word

        i = 0
        while i < len(word) and word[i] in "bcdfghjklmnpqrstvwxz":
            i += 1

        #At this point, i is the number of leading consonants in the word.
        leadingConsonants = word[:i]   #the first i characters
        rest = word[i:]                #the rest of the word

    pigLatinWord = rest + leadingConsonants + "ay"
    if capitalize:
        pigLatinWord = pigLatinWord.capitalize()
    return pigLatinWord


while True:

    try:
        sentence = input("Please type a sentence: ")
    except EOFError:
        sys.exit(0)

    while sentence:
        i = 0
        while i < len(sentence) and not sentence[i].isalpha():
            i += 1

        #At this point, i is the number of leading non-letters
	#(spaces, punctuation marks, etc).
        leadingNonletters = sentence[:i]
        sentence = sentence[i:]
        print(leadingNonletters, end = "")

        if not sentence:
            #nothing left to translate
            break

        i = 0
        while i < len(sentence) and sentence[i].isalpha():
            i += 1

        #At this point, i is the number of leading letters in the sentence.
        word = sentence[:i]   #the leftmost surviving word in the sentence
        sentence = sentence[i:]
        print(pigLatin(word), end = "")

    print()   #Output a newline at the end of the translated sentence.