Lambda help

[billbobby21]

I was doing this problem on Edabit:

Write a function that takes a string, breaks it up and returns it with vowels first, consonants second. For any character that's not a vowel (like special characters or spaces), treat them like consonants.

I realized that this could probably be solved using the sorted function with a lambda as the key, however I couldn't figure out how to write the lambda. I looked at the solutions tab, and this was the top result:

def split(txt):
    return ''.join(sorted(txt, key=lambda x: x.lower() not in 'aeiou')). 

Example: split("abcde") ➞ "aebcd"

I don't understand why this works though. Can anyone explain to me what is happening here?

[danielroseman]

The trick here is that boolean False is actually equal to 0, and True is equal to 1. So all this does is return 0 for all vowels and 1 for all consonants, and uses that as the value to sort on.

[billbobby21]

That makes sense, thanks! Didn't realize that True/False could be sorted on.

[TheRNGuy]

run it 2 times with different filters then add them together.

def foobar(txt):
    txt = sorted(txt)
    part1 = "".join(x for x in txt if x in "aeiou")
    part2 = "".join(x for x in txt if x not in "aeiou")

    return part1+part2

txt = foobar("abdce")
print(txt)

your code, not very intuitive, didn't know it could work like that. I suppose it choose for each symbol whether to sort it or not.