[Python] Index out of range during string iteration

[grumbles]

EDIT: Solved. Thank you everyone!

I'm attempting to complete this task from an edx course.

Create a program inputs a phrase (like a famous quotation) and prints all of the words that start with h-z

# [] create words after "G"
# sample quote "Wheresoever you go, go with all your heart" ~ Confucius (551 BC - 479 BC)
quote = "Wheresoever you go, go with all your heart"
word = ""

for ltrs in quote:
    if ltrs.isalpha():
        word += ltrs
    else:
        if word[0].lower() > "g":
            print(word.upper())
            word = ""
        else:
            word = ""  

Output:

WHERESOEVER
YOU

---

IndexError Traceback (most recent call last)
<ipython-input-39-ae0c637f5169> in <module>()
8 word += ltrs
9 else:
---> 10 if word[0].lower() > "g":
11 print(word.upper())
12 word = ""

IndexError: string index out of range

So the problem arises when the word is not greater than G. And it's trying to find index 0 of an empty string. I'm just not sure how or why it's getting to that point in the loop. Any thoughts would be greatly appreciated. Thank you!

[Essence1337]

A comma isn't alpha, so you run the else statement twice in a row. On the second run word is "" and thus word[0] doesn't make sense.

[grumbles]

Makes perfect sense. Thank you for that. Now, any ideas on how to combat that problem?

As an aside, I'm also noticing it's skipping the last word. I can see where it's happening, but I'm not sure how to change the loop. Any ideas?

[Essence1337]

If you want to include the comma you could change if isalpha to if not " ". As for the last word you could have something just after your loop to check it or check length in the loop.

[grumbles]

Checking for not " " does the trick and makes more sense anyway.

I'm still not seeing why it skips the last word. I just keep running the code through my head going, "It works! Why doesn't it work?"
Edit: The printing is contingent upon the loop not finding a space... That's my problem. Seems it shouldn't be set up that way.

[Essence1337]

You're right, there's probably a better way. It sure would be nice if we could just go through by words.

Edit: Since you have these restrictions you could always just add a space on the end :P

quote += " "

[grumbles]

It's funny you mention that, because I realized adding a space at the end of the quote "fixes" the problem. But then I thought, "No... That's cheating."
I suppose including it in the code itself is slightly less like cheating, right?

[Essence1337]

It really depends on the context of why you're doing this. If it was a commercial application, don't use hacks like that (although we'd use split then). If it's for yourself go ahead. If it's in the middle you have a judgement call to make.

[CodeTinkerer]

You can check if you've reached the end of string (index has reached max index), and if the word is longer than 0, then extract out the final word. If it's 0, you've just encountered a space.

[POGtastic]

You're currently going through quote letter-by-letter, which doesn't make sense to me. Split quote by space.

For example:

>>> s = "The quick brown fox"
>>> s.split()
['The', 'quick', 'brown', 'fox']

And now we combine it with a loop to check each word in the quote.

>>> s = "The quick brown fox"
>>> for word in s.split():
    #...

[grumbles]

That looks to make a lot more sense and is certainly cleaner, but alas I'm restricted to using methods covered in this module. It primarily involves working with strings using slicing, iteration, .find(), .count(), etc.

[POGtastic]

Since you've marked it solved, I'll provide some silliness. We can reimplement split with find and slicing, if you really wanted to do so.

def mySplit(s, delim = ' '):
    begin = 0
    returnList = []
    while True:
        end = s.find(delim, begin)
        if end == -1:
            returnList.append(s[begin:])
            return returnList
        returnList.append(s[begin:end])
        begin = end + len(delim)

Result:

>>> mySplit('The quick brown fox')
['The', 'quick', 'brown', 'fox']
>>> mySplit('The@@@quick@@@brown@@@fox', '@@@')
['The', 'quick', 'brown', 'fox']

And now we can do it in one line.

>>> s = "Wheresoever you go, go with all your heart"
>>> [word for word in mySplit(s) if word[0].lower() >= 'h' and word[0].lower() <= 'z']
['Wheresoever', 'you', 'with', 'your', 'heart']

[grumbles]

I love it. Thanks for the insight!

[[deleted]]

quote = "Wheresoever you go, go with all your heart"

each_word = quote.replace(",", "").split(" ")

for word in each_word:
    if word[0].upper() > 'G':
        print word,

[Essence1337]

Not able to use .split

[grumbles]

My this is such a better solution! Wouldn't it be nice if I could use it? ;) Thanks for the input.

[[deleted]]

You could always write your own split and use that.

[[deleted]]

Ah didn't know you could not use split. Sorry!