python输出字典keys的第一个

Method #1 : Using list() + keys() The combination of the above methods can be used to perform this particular task. In this, we just convert the entire dictionaries’ keys extracted by keys() into a list and just access the first key. Just one thing you have to keep in mind while using this i.e it’s complexity. It will first convert the whole dictionary to list by iterating over each item and then extract its first element. Using this method complexity would be O(n). filter_none edit play_arrow brightness_4 # Python3 code to demonstrate working of # Getting first key in dictionary # Using keys() + list() # initializing dictionary test_dict = {'Gfg' : 1, 'is' : 2, 'best' : 3} # printing original dictionary print("The original dictionary is : " + str(test_dict)) # Using keys() + list() # Getting first key in dictionary res = list(test_dict.keys())[0] # printing initial key print("The first key of dictionary is : " + str(res)) Output : The original dictionary is : {'best': 3, 'Gfg': 1, 'is': 2} The first key of dictionary is : best Method #2 : Using next() + iter() This task can also be performed using these functions. In this, we just take the first next key using next() and iter function is used to get the iterable conversion of dictionary items. So if you want only the first key then this method is more efficient. Its complexity would be O(1). filter_none edit play_arrow brightness_4 # Python3 code to demonstrate working of # Getting first key in dictionary # Using next() + iter() # initializing dictionary test_dict = {'Gfg' : 1, 'is' : 2, 'best' : 3} # printing original dictionary print("The original dictionary is : " + str(test_dict)) # Using next() + iter() # Getting first key in dictionary res = next(iter(test_dict)) # printing initial key print("The first key of dictionary is : " + str(res)) Output : The original dictionary is : {'best': 3, 'Gfg': 1, 'is': 2} The first key of dictionary is : best copy from https://www.geeksforgeeks.org/python-get-the-first-key-in-dictionary/