defaultdict:使用dict时,如果引用的Key不存在,就会抛出KeyError。如果希望key不存在时,返回一个默认值,就可以用defaultdict fromcollectionsimportdefaultdict dd=defaultdict(lambda:'N/A')#即key不存在时返回设置的默认值dd['k1']='abc'print(dd['k1'])#abcprint
In Python, the for loop is particularly versatile and user-friendly. It directly iterates over items of any sequence (such as a list or string), in the order that they appear, without requiring the indexing used in some other languages. This feature simplifies the process of looping through ...
So I made this list of the high points, what’s in each version of Python 2.x. Items with a star were introduced with a __future__ import. Update: I’ve now collected all the “What’s in which Python”s onto a single page:What’s in which Python. BTW: there’s alsoWhat’s ...