Sum dict values under the same key

Question

I have a list of items and values:

users_lst = [' spotify: 50.4\n', 'pandora: 23.4\n', 'pandora: 22.1\n', '\n', 'applemusic: \n]

I want to convert it to a dictionary, like this:

users = {'spotify': 50.4, 'pandora': 45.5}

My current code doesn't sum up the values for pandora:

users_lst = ['spotify: 50.4\n', 'pandora: 23.4\n', 'pandora: 22.1\n']

for i in users_lst:
  i = i.split(':')
  key = i[0]
  value = i[1]

  users[key] = value

print(users) #output: {'spotify': ' 50.4\n', 'applemusic': ' 22.1\n'}

Any pointers would be much appreciated. Prefer to use a solution without importing modules.

*Edit: updated the list to include non-float-type, blank and leading/trailing space cases

Answer 1

I can use a simple for loop and bunch of string cleaning operations like this to solve the problem,

users_lst = ['spotify: 50.4\n', 'pandora: 23.4\n', 'pandora: 22.1\n']

d = dict()
for item in users_lst:
    key, val = item.split(":")
    val = float(val.strip().replace("\n", ""))
    if key not in d:
        d[key] = val
    else:
        d[key] = d[key] + val
        
        
print(d) # {'spotify': 50.4, 'pandora': 45.5}

You can use dict.get() method and eliminate the use of if else checks like this,

users_lst = ['spotify: 50.4\n', 'pandora: 23.4\n', 'pandora: 22.1\n']

d = dict()
for item in users_lst:
    key, val = item.split(":")    
    d[key] = d.get(key, 0) + float(val)
        
        
print(d) # {'spotify': 50.4, 'pandora': 45.5}

Answer 2

Using collections.defaultdict

Ex:

from collections import defaultdict

users_lst = ['spotify: 50.4\n', 'pandora: 23.4\n', 'pandora: 22.1\n']
result = defaultdict(float)

for i in users_lst:
    key, value = i.strip().split(":")
    result[key] += float(value)
    
print(result)  # OR print(dict(result))

Output:

defaultdict(<class 'float'>, {'spotify': 50.4, 'pandora': 45.5})

Answer 3

There is many way to do this:

users_lst = ['spotify: 50.4\n', 'pandora: 23.4\n', 'pandora: 22.1\n']

user = dict()
for item in users_lst:
    key, val = item.split(":")
    val = float(val.strip())
    user[key] = user.get(key,0)+value

Answer 4

for i in users_lst:
  key, value = i.strip().split(':')
  users[key] = users.get(key, 0.0) + float(value)