How to add values of a key without losing any value in dictionary python when merging two list as di-CodePudding

I have two list of dictionaries which look like the following:

name = ['A','A','B','B','C','D','D','D']
num = [10, 20, 30, 40, 50, 60, 70, 80]

I want to merge them as 'name' for key and 'num' for value of the dictionary. But for each key if it has more than one value I want to add them without losing any 'num'. I tried to do it as

dict={}
for key,value in zip(name,num):
    if key not in dict:
        dict[key]=[value]
    else:
        dict[key].append(value)
print(dict)

I got output like

{'A': [10, 20], 'B': [30, 40], 'C': [50], 'D': [60, 70, 80]}

I want the final output to be like:

{'A': 30, 'B': 70, 'C': 50, 'D': 210}

Here every item for each key will be added rather than showing the list. How can I solve this?
Thanks

CodePudding user response：

Try this:

name = ['A', 'A', 'B', 'B', 'C', 'D', 'D', 'D']
num = [10, 20, 30, 40, 50, 60, 70, 80]
dict = {}
for key, value in zip(name, num):
    if key not in dict:
        dict[key] = value
    else:
        dict[key]  = value
print(dict)

CodePudding user response：

instead of appending you need to add values

dict_={}
for key,value in zip(name,num):
    if key not in dict_:
        dict_[key]=value
    else:
        dict_[key]=dict_[key] value
print(dict_)

CodePudding user response：

Instead of appending the values of same key to a list, just add them while iterating.

Something like below.

name = ['A','A','B','B','C','D','D','D']
num = [10, 20, 30, 40, 50, 60, 70, 80]

dict={}
for key,value in zip(name,num):
    if key not in dict:
        dict[key]=value
    else:
        dict[key] =value
print(dict)

CodePudding user response：

Consider using collections.Counter:

from collections import Counter

name = ['A', 'A', 'B', 'B', 'C', 'D', 'D', 'D']
num = [10, 20, 30, 40, 50, 60, 70, 80]
c = Counter()
for key, value in zip(name, num):
    c[key]  = value
d = dict(c)
print(d)

Or collections.defaultdict:

from collections import defaultdict

name = ['A', 'A', 'B', 'B', 'C', 'D', 'D', 'D']
num = [10, 20, 30, 40, 50, 60, 70, 80]
d = defaultdict(int)
for key, value in zip(name, num):
    d[key]  = value
d = dict(d)
print(d)

Output:

{'A': 30, 'B': 70, 'C': 50, 'D': 210}