Is there a possible way to delete an item using position in the dictionary in Python?-CodePudding

so I ran into this problem. Let's say I have a dictionary, and I want to delete the last item without knowing the item's key name. How would I do so?

CodePudding user response：

You pop the last item like this:

dictionary = {'a': 2, 'd': 3}
last_key = list(dictionary)[-1]
dictionary.pop(last_key)
print(dictionary)

Output

{'a': 2}

From Python3.7 dicts keep the order of keys. So, list(dictionary) represents keys in their insertion order

CodePudding user response：

You could probably use popitem()

(from Python 3.5 for OrderedDict, 3.7 for all dictionaries):

d = {'a':1, 'b':2,'c':3}

d.popitem() # ('c',3)

print(d)

{'a': 1, 'b': 2}

popitem() works like a LIFO queue (stack) so it removes the last added key. To delete the first item, you can use popitem(False) which works like a FIFO queue.

To delete some other arbitrary position, you can use itertools.islice to help:

from itertools import islice

d = {'a':1, 'b':2,'c':3,'d':4,'e':5}

del d[next(islice(d,2,None))]  # delete at index 2

print(d)

{'a': 1, 'b': 2, 'd': 4, 'e': 5}

This still needs to run through keys sequentially but at least it doesn't create an intermediate data structure (list) to do so.