Python | Get the first key in dictionary
Many times, while working with Python, we can have a situation in which we require to get the initial key of the dictionary. There can be many specific uses of it, either for checking the indexing and many more of these kinds. Let’s discuss certain ways in which this task can be performed.
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).
# Python3 code to demonstrate working of# Getting first key in dictionary# Using keys() + list() # initializing dictionarytest_dict = {'Gfg' : 1, 'is' : 2, 'best' : 3} # printing original dictionaryprint("The original dictionary is : " + str(test_dict)) # Using keys() + list()# Getting first key in dictionaryres = list(test_dict.keys())[0] # printing initial keyprint("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).
# Python3 code to demonstrate working of# Getting first key in dictionary# Using next() + iter() # initializing dictionarytest_dict = {'Gfg' : 1, 'is' : 2, 'best' : 3} # printing original dictionaryprint("The original dictionary is : " + str(test_dict)) # Using next() + iter()# Getting first key in dictionaryres = next(iter(test_dict)) # printing initial keyprint("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
Last Updated on October 28, 2021 by admin