I was just working on a Python caching system using the first-in-first out (FIFO) policy, when I encountered the challenge of removing the first item in a Python dictionary. My first inclination was to look this up online.
It took me some time to figure it out, so I decided to put together this post so that anyone else looking forward to removing the first item in a Python dictionary can achieve that easily.
Let's get into it. I will first give you the solution and then explain it in an easy-to-understand way for you.
Remove the first item in a Python dictionary
# Assuming you have a dictionary called my_dict
my_dict = {firstname: 'Obed', surname: 'Ehoneah', age: '99'}
# Get the key for the first item
first_key = next(iter(my_dict.keys()))
# Go ahead an delete the item from the dictionary
del my_dict[first_key]
Alternatively, you can use the pop() method in place of the del function as shown below.
# Assuming you have a dictionary called my_dict
my_dict = {firstname: 'Obed', surname: 'Ehoneah', age: '99'}
# Get the key for the first item
first_key = next(iter(my_dict.keys()))
# Go ahead an delete the item from the dictionary
my_dict.pop(first_key)
Now let's get to the explanations.
What you need to know about Python dictionaries to get this right
Prior to Python 3.7, dictionaries were considered unordered sequence of data but there are now considered to be ordered.
However, even though they are ordered, they are not indexable. This means that the data in a Python dictionary does not have an index and therefore cannot be accessed directly with their position in the dictionary.
The ideal way to access any data or item in a Python dictionary will be to use its key A dictionary's key plays the same role an index plays in other order sequences like lists and tuples.
Unfortunately there may be times when you need to access a specific data in a certain position of the dictionary while not knowing the key for that particular item. A practical example is what I faced when I was implementing a FIFO caching system with Python dictionary.
I was supposed to check and delete the very first item in the dictionary if the allocated space for the cache (i.e: the number of items to be stored in the dictionary) has been exceeded.
In such a case, I don't know the specific key for the item I would want to delete and therefore I cannot easily delete it.
The solution to this problem is therefore to find a way to get the key for the item at position one (or the specific position you are looking for).
I was able to achieve this with the combination of the next() function and the iter() function.
first_key = next(iter(my_dict.keys()))
The .keys() when used on a Python dictionary, returns a view object of the keys of that dictionary.
The iter() function is a built-in Python function that returns an iterator object. When used on the keys of the dictionary, it turns them into an iterator which makes them behave like the common iterators (ie: lists and tuples).
This gives them an order and kind of index them such that you can move from one key to the other with the help of the next() function.
When called for the first time, the next() function will give us the first key. So, if you are looking for a specific position in the dictionary then you would have to know how many times to run the nex() function in order to get it.
In this example, we are interested in only the first position so we only call next() once and we get the key for the first item.
Conclusion
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