Accessing elements in dictionary of dictionaries

Question

I am parsing some information from a CSV File and am inputting it into a dict of dicts. The inner dict v contains the following elements {'140725AD4': <mod.City object at 1x3259C2D1>, '631315AD2': <mod.City object at 0x023A4870>} . How would I access the object <mod.city object at 0x0138C3B0> for example?

Thank You.

Answer 1

Having a structure like the following:

john = {
    "name": "John",
    "family": {
        "son": "Ret",
        "daughter": "Pat"
    }
}

You can access the John son's name like this:

john['family']['son']

This will return "Ret"

In your case, if City object is a DICT you can use:

dict['140725AD4']['population']

If your City object is just a Class you can do

dict['140725AD4'].getPopulation()

or

dict['140725AD4'].population

How it works? A dictionary is a hashmap of pairs (name, value). Whenever you call a name the value is given. In Python, the value can be anything, from int to a Class.

So when in a dict you ask for a name inside a dict like dict['name'] you get back the value associated with it. In this case its your City object. Then you can call anything related to the value: functions, variables...

Answer 2

Assuming this question is the follow up for this one - Updating Dictionary of Dictionaries in Python you would have to do this:

inner_dict = places["City"]
for _, city_obj in inner_dict.items():
    print city_obj.population # Assuming population is one of the member variables of the class mod.city