How to extract from a list of objects a list of specific attribute?

Question

I have a list of objects. Object has 3 string attributes. I want to make a list containing only a specific attribute from class.

Is there any built-in functions to do that?

score 81 · Accepted Answer · answered Mar 24 '09 at 14:36

81

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)

answered Mar 24 '09 at 14:36

Jarret Hardie

that's not a built-in if you need to import. ;) http://docs.python.org/library/functions.html – SilentGhost Mar 24 '09 at 14:44
10

I plead nuance: "built-in" != "__builtins__'. Well, that's my story and I'm sticking to it, officer. :-) – Jarret Hardie Mar 24 '09 at 14:59
and how to retrieve 2 (or more) attributes from this class? – MrT77 Dec 28 '20 at 19:17
I was looking for `o["myattr"]` which you might infer from the object structure. This is the correct way. – Chaim Eliyah Jun 29 '21 at 20:12

score 10 · Answer 2 · answered Mar 24 '09 at 14:35

10

are you looking for something like this?

[o.specific_attr for o in objects]

answered Mar 24 '09 at 14:35

SilentGhost

score 9 · Answer 3 · answered Mar 24 '09 at 14:34

9

The first thing that came to my mind:

attrList = map(lambda x: x.attr, objectList)

answered Mar 24 '09 at 14:34

Coffee on Mars

RossFabricant · Answer 4 · 2009-03-24T17:25:05.453

1

Assuming you want field b for the objects in a list named objects do this:

[o.b for o in objects]

edited Mar 24 '09 at 17:25

answered Mar 24 '09 at 14:33

RossFabricant

4 Answers4