generate a dict mapping items by the given field of each object

index.py

"""
Generate a mapping of a list of objects by the given attr.
"""

def index(objects, attr):
    return {getattr(obj, attr): obj for obj in objects}

# Example

class Person(object):
    def __init__(self, name, email, age):
        self.name = name
        self.email = email
        self.age = age

people = [
    Person('one', 'one@people.com', 1),
    Person('two', 'two@people.com', 2),
    Person('three', 'three@people.com', 3)
]

by_email = index(people, 'email')
by_name = index(people, 'name')

assert by_name['one'] is people[0]
assert by_email['two@people.com'] is people[1]