Automate the boring stuff with Python: Comma Code

Question

Currently working my way through this beginners book and have completed one of the practice projects \'Comma Code\' which asks the user to construct a program which:

Answer 1

Here's a solution that handles the Oxford comma properly. It also copes with an empty list, in which case it returns an empty string.

def list_thing(seq):
    return (' and '.join(seq) if len(seq) <= 2
        else '{}, and {}'.format(', '.join(seq[:-1]), seq[-1]))

spam = ['apples', 'bananas', 'tofu', 'cats']

for i in range(1 + len(spam)):
    seq = spam[:i]
    s = list_thing(seq)
    print(i, seq, repr(s))

output

0 [] ''
1 ['apples'] 'apples'
2 ['apples', 'bananas'] 'apples and bananas'
3 ['apples', 'bananas', 'tofu'] 'apples, bananas, and tofu'
4 ['apples', 'bananas', 'tofu', 'cats'] 'apples, bananas, tofu, and cats'

---

FWIW, here's a slightly more readable version using an if-else statement instead of a conditional expression:

def list_thing(seq):
    if len(seq) <= 2:
        return ' and '.join(seq)
    else:
        return '{}, and {}'.format(', '.join(seq[:-1]), seq[-1])    

And here's a slightly less readable version, using an f-string:

def list_thing(seq):
    if len(seq) <= 2:
        return ' and '.join(seq)
    else:
        return f"{', '.join(seq[:-1])}, and {seq[-1]}"   

---

Note that Martijn's code produces 'apples, and bananas' from the 2 item list. My answer is more grammatically correct (in English), however Martijn's is more technically correct because it does exactly what's specified in the OP's quote (although I disagree with his handling of the empty list).