I have a list li:
[
{name: "Tom", age: 10},
{name: "Mark", age: 5},
{name: "Pam", age: 7}
]
I want to get the index of the item that has a certain name. For example, if I ask for "Tom" it should give me: 0. "Pam" should give me 2.
Asked
Active
Viewed 2.9k times
10
Bastien Léonard
- 60,478
- 20
- 78
- 95
dkgirl
- 4,489
- 7
- 24
- 26
-
1Any reason you don't just use a dictionary to begin with? – Keith Jan 01 '11 at 12:10
2 Answers
27
>>> from operator import itemgetter
>>> map(itemgetter('name'), li).index('Tom')
0
>>> map(itemgetter('name'), li).index('Pam')
2
If you need to look up a lot of these from the same list, creating a dict as done in Satoru.Logic's answer, is going to be a lot more efficent
John La Rooy
- 295,403
- 53
- 369
- 502
-
2+1, I didn't know this. I had assumed that this problem is too trivial to have a library function like `itemgetter` and always looped over the dict items :D – 0xc0de Jan 21 '12 at 14:27
-
in python3 it seems the map needs to be wrapped in a list to provide the index method – Vincent De Smet May 28 '17 at 14:01
17
You may index the dicts by name
people = [ {'name': "Tom", 'age': 10}, {'name': "Mark", 'age': 5} ]
name_indexer = dict((p['name'], i) for i, p in enumerate(people))
name_indexer.get('Tom', -1)
satoru
- 31,822
- 31
- 91
- 141