Question

lets assume the following simple Object:

class Mock:
    def __init__(self, name, age):
        self.name = name
        self.age = age

then I have a list with some Objects like this:

myList = [Mock("Dan", 34), Mock("Jack", 30), Mock("Oli", 23)...]

Is there some built-in feature where I can get all Mocks with an age of ie 30?
Of course I can iterate myself over them and compare their ages, but something like

find(myList, age=30)

would be nice. Is there something like that?

Answer 1

You might want to pre-index them –

from collections import defaultdict

class Mock(object):
    age_index = defaultdict(list)

    def __init__(self, name, age):
        self.name = name
        self.age = age
        Mock.age_index[age].append(self)

    @classmethod
    def find_by_age(cls, age):
        return Mock.age_index[age]

Edit: a picture is worth a thousand words:

X axis is number of Mocks in myList, Y axis is runtime in seconds.

• red dots are @dcrooney’s filter() method
• blue dots are @marshall.ward’s list comprehension
• green dots hiding behind the X axis are my index 😉