![[python] defaultdict](https://img.php.cn/upload/article/000/000/000/172156504344878.jpg)
normal dict raises Keyerror after querying keys that don't exist
>>> from collections import defaultdict
>>> my_dict = {"one": 1, "two": 2}
>>> my_dict["three"]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: 'three'
but by using a lamda in a deafultdict we can set default values for undefined keys
# create a default dict, from a dict >>> my_def_dict = defaultdict(lambda: -1, my_dict) >>> my_def_dict["zero"] -1 # create an empty default dict >>> empty_def_dict = defaultdict(lambda: true) # add key-value pairs here
The above is the detailed content of [python] defaultdict. For more information, please follow other related articles on the PHP Chinese website!
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
