Can I append to a list in a dictionary?
test = {'food' : 'apple'}
Is there a command to add 'banana' and turn it into
test = { 'food': ['apple','banana'] }
Thank you
Asked
Active
Viewed 313 times
0
-
2`test['food'].append('banana')`. – Li-aung Yip May 14 '12 at 04:36
-
1That isn't a `list`, it is a string or `str` in python. It becomes a `list` in your second example though. – jamylak May 14 '12 at 04:39
4 Answers
5
No, since it isn't a list in the first place.
test['food'] = [test['food'], 'banana']
Ignacio Vazquez-Abrams
- 776,304
- 153
- 1,341
- 1,358
4
You need to create a dict where the values are lists:
test = {'food' : ['apple']}
test['food'].append('banana')
vz0
- 32,345
- 7
- 44
- 77
3
The simplest solution would just be to just make the value of your hash a list, that may contain just one element. Then for example, you might have something like this:
test = {'food' : ['apple']}
test['food'].append('banana')
-
2+1 I think it's likely the OP was trying append, but overlooked the missing `[]` – John La Rooy May 14 '12 at 04:46
1
I'd recommend using a defaultdict in this case, it's pretty straightforward to deal with dictionaries of lists, since then you don't need two separate cases every time you modify an entry:
import collections
test = collections.defaultdict(list)
test['food'].append('apple')
test['food'].append('banana')
print test
# defaultdict(<type 'list'>, {'food': ['apple', 'banana']})
Adam Rosenfield
- 390,455
- 97
- 512
- 589
-
It is straightforward to do this without a `defaultdict` too: `test.setdefault("food", []).append("apple")` – kindall May 14 '12 at 05:12