attrs = [o.attr for o in objs] was the right code for making a list like the one you describe. Don't try to subclass list for this. Is there something you did not like about that snippet?

>>> class new_class():
...   def __init__(self, number):
...     self.multi = int(number) * 2
...     self.str = str(number)
... 
>>> a = new_class(2)
>>> a.__dict__
{'multi': 4, 'str': '2'}
>>> a.__dict__.keys()
dict_keys(['multi', 'str'])

You may also find pprint helpful.

A list comprehension would work just fine:

[o.my_attr for o in my_list]

But there is a combination of built-in functions, since you ask :-)

from operator import attrgetter
map(attrgetter('my_attr'), my_list)

In Python, to access object attribute the syntax is

<object instance>.<attribute_name>

In your case, [index].

As Paul said, use dir(<object_instance>[index]) to get all attribute, methods associated object instance.

You can also use for loop to iterate over

for <obj> in <object_list>:
    <obj>.<attribute_name>

Hope it helps

If you have the slice, you can iterate over it in a comprehension:

[obj.attr for obj in slice]

where slice is

a[2::2,::2]
a[:,2]
a[4:,4:]

etc.

Use the built-in function dir().

List comprehension is what you're after:

list_of_objects = [Object_1, Object_2, Object_3]
[x.time for x in list_of_objects]

In hindsight I should've realised the code would think I demanded an attribute from the list itself, not the items inside

Actually, code doesn't "think", it is only executed. And the runtime doesn't "think" either, it just executes the code provided. But those minor conceptual nuances set aside, your diagnostic is right: deck.face looks up the attribute named "face" on the deck (list) object itself.

If your question is "how to print (or collect or do whatever with) the face attribute for each card in deck, the simple solution is to iterate on the list:

for card in deck:
    print(card.face)

or if you want to build a list of face values:

faces = [card.face for card in deck]

Now if it's an exercise in OO design, you may want to reconsider the use of a list to represent a "deck" object - a cards deck is actually not a list.

If you want a list of dictionaries of object attributes:

# the list of attributes to get from each object
attrs = ['attr1', 'attr2']

# using dictionary comprehension to generate the list of attributes and their values
attr_vals_dict = [{a:getattr(o, a) for a in attrs} for o in objects]

Output:

[{'attr1': 1, 'attr2': 2}, {'attr1': 3, 'attr2': 4}, {'attr1': 'banana', 'attr2': 'apple'}]

As far as getting the dynamic list of attributes in the first place, that's already been answered here.

In terms of performance, to create a list of ages, [i.get_age() for i in person_list] is about as good as you'll get. The only real way to avoid this is to adjust the mean, median, and mode functions to accept a key parameter (much like the built-in sort function does) so that each function will access the correct attribute of the object. I wouldn't worry about removing that list comprehension though. Unless person_list is huge, and you require this code to run often, and as fast as possible, that would be a premature optimization.

Another way to potentially speed it up would be to have a single function that iterates the list once, and calculates all three statistics in one go. Again though, I would consider that to be premature unless you had a very good reason to optimize that.

Your solution is fine until you run into a situation in which it isn't performing well. Favor readability and simplicity until performance becomes an actual concern (or you have good reason to believe that it will become an actual concern in the near future).