如何从列表中创建多个键，每个键都分配给一个唯一的数组？

Question

My goal is to build a dictionary in Python. My code seems to work. However, when I attempt to append a value to a single key the value is appended to multiple keys. I understand this is because the fromkeys method assigns multiple keys to the same list. How do I create multiple keys from a list with each assigned to a unique array?

#Create an Array with future dictionary keys
x = ('key1', 'key2', 'key3')

#Create a Dictionary from the array

myDict = dict.fromkeys(x,[])

#Add some new Dictionary Keys
myDict['TOTAL'] = []

myDict['EVENT'] = []



#add an element to the Dictionary works as expected

myDict['TOTAL'].append('TOTAL')

print(myDict)

#{'key1': [], 'key2': [], 'key3': [], 'TOTAL': ['TOTAL'], 'EVENT': []}



#add another element to the Dictionary
#appending data to a key from the x Array sees the data appended to all the keys from the x array
myDict['key1'].append('Entry')

print(myDict)

#{'key1': ['Entry'], 'key2': ['Entry'], 'key3': ['Entry'], 'TOTAL': ['TOTAL'], 'EVENT':
# []}

Answer 1

Key1, key2, and key3 all contain a reference to a single list, which you are appending to. They don't each include a unique list.

Jared's answer above is correct. You can also write:

myDict = dict()
for key in x:
  myDict[key] = []

which does the same thing.

Answer 2

Based on the answers so far I cobbled together an approach that works. Is this the 'python' or 'python optimal' way to do this?

#Create an Array with future dictionary keys
x = ('key1', 'key2', 'key3')


#Create a Dictionary from the array

tempDict = dict.fromkeys(x,[])


myDict = {}



for key in tempDict.keys():
    
    print(key)
    
    myDict[key] = []


#Add some new Dictionary Keys

myDict['TOTAL'] = []

myDict['EVENT'] = []

print(myDict)


#add an element to the Dictionary works as expected   
myDict['TOTAL'].append('TOTAL')
print(myDict)
#{'key1': [], 'key2': [], 'key3': [], 'TOTAL': ['TOTAL'], 'EVENT': []}



#add another element to the Dictionary
#appending data to a key from the x  Array sees the data appended to all the x keys.
myDict['key1'].append('Entry') 
print(myDict)

#{'key1': ['Entry'], 'key2': [], 'key3': [], 'TOTAL': ['TOTAL'], 'EVENT':
# []}