Enforce items at beginning and end of list

Question

How can I modify this list so that all p\'s appear at the beginning, the q\'s at the end, and the values in between are sorted alphabetically?

Answer 1

Use the key parameter in sorted:

l = ['f','g','p','a','p','c','b','q','z','n','d','t','q']

def key(c):
    if c == 'q':
        return (2, c)
    elif c == 'p':
        return (0, c)
    return (1, c)


result = sorted(l, key=key)
print(result)

Output

['p', 'p', 'a', 'b', 'c', 'd', 'f', 'g', 'n', 't', 'z', 'q', 'q']