B11 - filter

students = [
    {"name": "Hermione", "house": "Gryffindor"},
    {"name": "Harry", "house": "Gryffindor"},
    {"name": "Ron", "house": "Gryffindor"},
    {"name": "Draco", "house": "Slytherin"},
]

def is_gryffindor(s):
    return s["house"] == "Gryffindor"

gryffindors = filter(is_gryffindor, students)

for gryffindor in sorted(gryffindors, key=lambda s: s["name"]):
    print(gryffindor["name"])

• filter takes two arguments
• the first is a function that returns True or False
• the second is the sequence which is to be filtered
• furthermore, a lambda function can be used to simplify it, removing the need to have a defined function

gryffindors = filter(lambda s: s["house"] == "Gryffindor", students)