Remove an item from a dictionary when its key is unknown

Question

What is the best way to remove an item from a dictionary by value, i.e. when the item's key is unknown? Here's a simple approach:

for key, item in some_dict.items():
    if item is item_to_remove:
        del some_dict[key]

Are there better ways? Is there anything wrong with mutating (deleting items) from the dictionary while iterating it?

Answer 1

The dict.pop(key[, default]) method allows you to remove items when you know the key. It returns the value at the key if it removes the item otherwise it returns what is passed as default. See the docs.'

Example:

>>> dic = {'a':1, 'b':2}
>>> dic
{'a': 1, 'b': 2}
>>> dic.pop('c', 0)
0
>>> dic.pop('a', 0)
1
>>> dic
{'b': 2}