将对象列表转换为字典

Question

I have a list of city objects in which each object has a state and a name. I want to convert this list to a dictionary where the state name is the key and the value is a list of all the cities. For example,

"California" : [Ashland, Englewood, ...]

Right now I have

newDictionary = dict((x.state, x.name) for x in objectList)

but it is only adding the last city of each state instead of all of them. What is the best way to do this?

Answer 1

You could do it like this (with more Pythonic variable names :-)):

state_with_cities = {}
for x in city_data_list:
    state_with_cities[x.state] = state_with_cities.get(x.state, []) + [x.name]

Answer 2

You can try setdefault .

stateWithCities = {}
for x in cityDataList:
    stateWithCities.setdefault(x.state, []).append(x.name)