How to add new objects to nested dictionary?

Question

Given the below object, how to add a new city "losangeles" in "california"? Given a country, state, city and attributes for the city, how can I update the object? (I am pretty new to python)

myplaces = {
  "unitedstates": {
    "california": {
      "sanfrancisco": {
        "description": "Tech heaven",
        "population": 1234,
        "keyplaces": ["someplace1",
          "someplace2"]
      }
    }
  },
  "india": {
    "karnataka": {
      "bangalore": {
        "description": "IT hub of India",
        "population": 12345,
        "keyplaces": ["jpnagar",
          "brigade"]
      },
      "mysore": {
        "description": "hostoric place",
        "population": 12345,
        "keyplaces": ["mysorepalace"]
      }
    }
  }
}

I tried adding elements as below (like how it is done in PHP):

myplaces['unitedstates']['california']['losangeles']['description'] = 'Entertainment'

Edit: This is not a duplicate. I am looking for a generic way to add items.

possible duplicate of [Python add new item to dictionary](http://stackoverflow.com/questions/6416131/python-add-new-item-to-dictionary) — Bhargav Rao, May 15 '15 at 11:07

score 3 · Answer 1 · answered May 15 '15 at 11:08

3

You've almost got it -

myplaces['unitedstates']['california']['losangeles'] = {'description':'Entertainment'}

answered May 15 '15 at 11:08

kaz

1,190
8
19

of course this all depends on what `myplaces` contains, so it's not a *generic* solution. – Karoly Horvath May 15 '15 at 11:10
What if I need to add a new state 'Michigan'? `myplaces['unitedstates']['michigan']['annarbour'] = {'description':'Cold place'}` doesn't work right? – softwarematter May 15 '15 at 11:13
Correct, you'd have to do something like: `myplaces['unitedstates']['michigan'] = {} ` first. – kaz May 15 '15 at 11:15
So I need to add a check at each level? – softwarematter May 15 '15 at 11:15
you want something like `addcity(myplaces, ('unitedstates', 'michigan', 'annarbour'), {.....});` and then in the implementation use a loop and create the "nodes" if necessary. – Karoly Horvath May 15 '15 at 11:19

score 2 · Answer 2 · answered May 15 '15 at 11:30

You could create a tree using a dictionary with a default value of a tree:

>>> from collections import defaultdict

>>> def tree():
...     return defaultdict(tree)


>>> myplaces = tree()
>>> myplaces['unitedstates']['california']['losangeles']['description'] = 'Entertainment'

score 0 · Answer 3 · answered May 15 '15 at 11:10

0

Try:

myplaces['unitedstates']['california']['losangeles']={}
myplaces['unitedstates']['california']['losangeles']['description']='Entertainment'

answered May 15 '15 at 11:10

laila

1,009
3
15
27

How to add new objects to nested dictionary?

3 Answers3