CODEWITHSUNDEEP
pythondictionarykey
Luke Fox
Luke Fox

Reputation: 31

How do I add a string to a list in a dictionary?

I have to make a dictionary that will turn this list:

locations = [ 
  ['Lorraine Izaguirre', 'MA'], 
  ['Chris Clements', 'PA'], 
  ['Kari Bacon', 'PA'], 
  ['Chris Clements', 'NY'],
  ['Chris Clements', 'NJ'],
  ['Jamee Cheek', 'PA'],
  ['Kari Bacon', 'NY']
]

into:

{'Lorraine Izaguirre': ['MA'], 'Chris Clements': ['PA', 'NY', 'NJ'], 'Kari Bacon': ['PA', 'NY'], 'Jamee Cheek': ['PA']}

This is the code I have already made, but for some reason I keep getting an error saying that I can't append a string to a list. I am very confused, because I thought I was explicitly stating that state is a 1x1 list in the append statement. Any help would be appreciated.

def organize(locations):
  name_dict = {}
  for i in range(len(locations)-1):
    name = locations[i][0]
    state = locations[i][1]
    if name not in name_dict:
      name_dict.update({name:state})
    else:
      name_dict[name] = name_dict[name].append([state])
  return name_dict

Edit: Solved it, there were a couple issues

1.) pointed out below that I needed to change name_dict.update({name:state}) into name_dict.update({name:[state]})

2.) I needed to change range(len(locations)-1) into range(len(locations))

and 3.) change name_dict[name].append([state]) into name_dict[name].append(state)

Upvotes: 0

Views: 62

Answers (2)

DevLounge
DevLounge

Reputation: 8437

collections.defaultdict has been designed for this

from collections import defaultdict

def organize(locations):
    name_dict = defaultdict(list)
    for name, state in locations:
        name_dict[name].append(state)
  
    return name_dict

Upvotes: 0

Andrej Kesely
Andrej Kesely

Reputation: 195438

You can use dict.setdefault for the task:

locations = [
    ["Lorraine Izaguirre", "MA"],
    ["Chris Clements", "PA"],
    ["Kari Bacon", "PA"],
    ["Chris Clements", "NY"],
    ["Chris Clements", "NJ"],
    ["Jamee Cheek", "PA"],
    ["Kari Bacon", "NY"],
]

out = {}
for l, abbr in locations:
    out.setdefault(l, []).append(abbr)

print(out)

Prints:

{'Lorraine Izaguirre': ['MA'], 'Chris Clements': ['PA', 'NY', 'NJ'], 'Kari Bacon': ['PA', 'NY'], 'Jamee Cheek': ['PA']}

Upvotes: 2

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