python 知识点

【1】filter(function or None, iterable) --> filter object

filter(lambda x : x%2, [1,2,3,4,5]) --> [1,3,5]

【2】map(func, *iterables) --> map object

map(lambda x : x*2,  range(5)) --> [0,2,4,6,8]

【3】dict初始化方式 3种

dict() -> new empty dictionary

 |  dict(mapping) -> new dictionary initialized from a mapping object's
 |      (key, value) pairs
 |  dict(iterable) -> new dictionary initialized as if via:
 |      d = {}
 |      for k, v in iterable:
 |          d[k] = v
 |  dict(**kwargs) -> new dictionary initialized with the name=value pairs

 |      in the keyword argument list.  For example:  dict(one=1, two=2)

【4】issubclass(cls, class_or_tuple, /)

Return whether 'cls' is a derived from another class or is the same class

【5】isinstance(obj, class_or_tuple, /)

    Return whether an object is an instance of a class or of a subclass thereof.注意：当第一个参数需传入对象实例，而不能传入class，否则结果都为false，第二个参数需传入类，否则会抛出异常。