Turn the list of dictionaries into a single dictionary

user_7370374 0
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I've been trying to convert a list of dictionaries into a single dictionary in such a way where each key is <city>, <state> and each value is <county>.

In short I have a list that looks like this.

[{'city': 'Normal', 
  'county': 'Madison County', 
  'state': 'Alabama'},
 {'city': 'Birmingham', 
  'county': 'Jefferson County', 
  'state': 'Alabama'},
 {'city': 'Montgomery', 
  'county': 'Montgomery County', 
  'state': 'Alabama'}]

And I would like to change it into something like this

{'Normal, Alabama': 'Madison County',
 'Birmingham, Alabama': 'Jefferson County',
 'Montgomery, Alabama': 'Montgomery County'}

I tried dictionary comprehensions but can't seem to add two different keys at once.

So I know the code below will give me a dictionary with cities and counties for key value pairs

new_dict = {x['city']: x['county']  for x in counties}

However, how do I add two different keys? Something like new_dict = {x['city','state']: x['county'] for x in counties} won't work.

dictionary-comprehension dictionary python
3 Answers

You can use dict comprehension:

lst = [{'city': 'Normal',
  'county': 'Madison County',
  'state': 'Alabama'},
 {'city': 'Birmingham',
  'county': 'Jefferson County',
  'state': 'Alabama'},
 {'city': 'Montgomery',
  'county': 'Montgomery County',
  'state': 'Alabama'}]

output = {f"{dct['city']}, {dct['state']}": dct['county'] for dct in lst}
print(output)
# {'Normal, Alabama': 'Madison County', 'Birmingham, Alabama': 'Jefferson County', 'Montgomery, Alabama': 'Montgomery County'}

Here, you combine two keys by using f-string.

user_114508200

You can use string concatenation to form the key:

data = [{'city': 'Normal', 
  'county': 'Madison County', 
  'state': 'Alabama'},
 {'city': 'Birmingham', 
  'county': 'Jefferson County', 
  'state': 'Alabama'},
 {'city': 'Montgomery', 
  'county': 'Montgomery County', 
  'state': 'Alabama'}]
  
new_dict = {x['city'] + ", " + x['state']: x['county']  for x in data}

print(new_dict)

This outputs:

{'Normal, Alabama': 'Madison County', 'Birmingham, Alabama': 'Jefferson County', 'Montgomery, Alabama': 'Montgomery County'}
user_177698150

Why not just a simple for loop?

l = [
    {"city": "Normal", "county": "Madison County", "state": "Alabama"},
    {"city": "Birmingham", "county": "Jefferson County", "state": "Alabama"},
    {"city": "Montgomery", "county": "Montgomery County", "state": "Alabama"},
]

result = dict()
for x in l:
    city = x.get("city")
    state = x.get("state")

    key = f"{city}, {state}"
    value = x.get("county")

    result[key] = value

print(result)
user_62914390
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