能与lambda组合的五个常用内置函数
min(), max()
l = [1,-3,4,11,5,0.1] print(min(l,key=lambda x:x**2)) l = [1,-3,4,-11,5,0.1] print(max(l,key=lambda x:x**2))
注意min()、max()函数调用方式中,条件的传递使用 key作为关键字参数。
sorted()
l = [1,-3,4,-11,5,0.1] print(sorted(l,key=lambda x:x**2,reverse=True)) help(sorted)
sorted()函数有两个关键字参数,key用来设置排序条件,reverse为False为降序,Ture为升序。
filter()
l = [1,-3,4,-11,5,0.1] print(list(filter(lambda x:True if x%2==0 else False,l)))
filter()函数中func为位置参数,
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
class filter(object) | filter(function or None, iterable) --> filter object | | Return an iterator yielding those items of iterable for which function(item) | is true. If function is None, return the items that are true. | | Methods defined here: | | __getattribute__(self, name, /) | Return getattr(self, name). | | __iter__(self, /) | Implement iter(self). | | __new__(*args, **kwargs) from builtins.type | Create and return a new object. See help(type) for accurate signature. | | __next__(self, /) | Implement next(self). | | __reduce__(...) | Return state information for pickling. <filter object at 0x00000000023511D0> Process finished with exit code 0
map()
l = [1,-3,4,0,-11,5,0.1] print(list(map(lambda x:x**3,l)))
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
class map(object) | map(func, *iterables) --> map object | | Make an iterator that computes the function using arguments from | each of the iterables. Stops when the shortest iterable is exhausted. | | Methods defined here: | | __getattribute__(self, name, /) | Return getattr(self, name). | | __iter__(self, /) | Implement iter(self). | | __new__(*args, **kwargs) from builtins.type | Create and return a new object. See help(type) for accurate signature. | | __next__(self, /) | Implement next(self). | | __reduce__(...) | Return state information for pickling. [1, -27, 64, 0, -1331, 125, 0.0010000000000000002]
min(),max()返回值为原序列中的一个,sorter()返回序列与原序列值相同,只是顺序可能不一样;map(),filter()返回值为一个iterator(迭代器),可以用list()强制转换。