Iterate over a dictionary using 'for' loop in a class

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Iterating over dictionaries using 'for' loops 12 answers

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It seems you want to iterate over keys and values . You can accomplish this by iterating over the items() :

for channel_num, channel_det in self.dictionary.items():

In your case for something in self.dictionary: iterates only over the keys. And the keys are integers. But you try to unpack the integer into two values: channel_num, channel_det which is why it failed.

Additional comments:

You only need the values in your for -loop so you could also iterate over the values() only:

for channel_det in self.dictionary.values():

And the really advanced method would be to use a generator expression and the built-in sum function:

def find_total(self):
    return sum(channel_det['charge'] for channel_det in self.dictionary.values())

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你应该迭代字典的items ：

class DictionaryTest:
    def __init__(self, dictionary):
        self.dictionary = dictionary

    def find_total(self):
        total = 0
        for channel_num, channel_det in self.dictionary.items():
                               #Changed here only      ^   
            total += channel_det['charge']
        return total

channel_list = {1:{'name': 'Sony PIX', 'charge':3}, 2:{'name': 'Nat Geo Wild', 'charge':6}, 3:{'name': 'Sony SET', 'charge':3},
    4:{'name': 'HBO - Signature', 'charge':25}}



user_2 = DictionaryTest(channel_list)
print(user_2.find_total())

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