Put a symbol between every letter in a list of strings

Question

How would I put ! after every character in a list

listOne = ["hello","world"]

How do I turn that into:

["h!e!l!l!o","w!o!r!l!d"]

Attempt:

def turn(List):
    return [i for i in (list(lambda x: "%s!" % x,listOne))]
turn(listOne)

Returns:

['hello!',"world!"]

Is their another way to do this besides:

def turn(List):
    x = ""
    for word in words:
        for letter in word:
            x += "%s!" % letter
    return x
turn(listOne)

I'm not a big fan of doing things like that however I do realize that may be more pythonic than what I'm trying to do which is make it as few lines as possible so. Is this possible?

Answer 1

You can easily achieve this with the str.join() method, and list comprehension:

>>> listOne = ['!'.join(i) for i in listOne]
>>> listOne

Output

['h!e!l!l!o', 'w!o!r!l!d']

Alternatively, as abarnert suggested, you can use the bulit-in map function.

>>> listOne = list(map('!'.join, listOne))
>>> listOne
['h!e!l!l!o', 'w!o!r!l!d']

Hope this helps!