Sorted working differently with '&' in one of the list elements

Question

if we have a dict and convert it

a={'pop': 1, 'Christmas': 1, 'R&B': 2}

and then we use sorted

sorted(list(a))

why does it return this?:

['Christmas', 'R&B', 'pop']

Answer 1

>>> a={'pop': 1, 'Christmas': 1, 'R&B': 2}
>>> list(a)
['pop', 'Christmas', 'R&B']

list(a) is the keys in the dictionary and sorted() sorts the keys.

Answer 2

list(a) gives list of dictionary keys and sorted sorts it. Because your keys are a mix of uppercase and lowercase characters, you won't expect it to return in required way as uppercase letters are sorted before lowercase.

One way to handle this is to define a custom function like:

a = {'pop': 1, 'Christmas': 1, 'R&B': 2}

def lower(x):
    return x.lower()

print(sorted(list(a), key=lower))
# ['Christmas', 'pop', 'R&B']

If you are trying to sort by length of words, this would be the way:

a = {'pop': 1, 'Christmas': 1, 'R&B': 2}

print(sorted(list(a), key=len))
# ['pop', 'R&B', 'Christmas']