How to flip a string or list in Python, and how to flip a string in python

How to flip a string or list in Python, and how to flip a string in python

1. reversed

class reversed(object) |  reversed(sequence) -> reverse iterator over values of the sequence |   |  Return a reverse iterator |   |  Methods defined here: |   |  __getattribute__(...) |      x.__getattribute__('name') <==> x.name |   |  __iter__(...) |      x.__iter__() <==> iter(x) |   |  __length_hint__(...) |      Private method returning an estimate of len(list(it)). |   |  next(...) |      x.next() -> the next value, or raise StopIteration |   |  ---------------------------------------------------------------------- |  Data and other attributes defined here: |   |  __new__ = <built-in method __new__ of type object> |      T.__new__(S, ...) -> a new object with type S, a subtype of T

The processed object is an iteratable object, and the returned value is an iterator. Therefore, you can process string list and so on, as shown below:

In [54]: reversed([1,2,3])                                                                                                                                                                        Out[54]: <listreverseiterator at 0x7f835810c190>In [55]: reversed('123')                                                                                                                                                                          Out[55]: <reversed at 0x7f835810c2d0>In [56]: type(reversed('123'))Out[56]: reversedIn [57]: for i in reversed('123'):   ....:     print i   ....:     321

PS: The functions of the built-in _ reversed _ () method of list are similar to those of this method. For details, refer to 2.

 

2. reverse

Reverse is a built-in method of list, so it can only be used for list, as shown below:

In [62]: l = [1, 2, 3]                                                                                                                                                                            In [63]: l.reverse()In [64]: lOut[64]: [3, 2, 1]

 

_ Reversed __()

In [65]: l.__reversed__()Out[65]: <listreverseiterator at 0x7f835810ca90>In [66]: for i in l.__reversed__():                                                                                                                                                                  ....:     print i   ....:     123

 

3. Slice

The simplest method is to use string and list

In [73]: sOut[73]: 'i am a student.'In [74]: s[::-1]Out[74]: '.tneduts a ma i'In [75]: lOut[75]: [3, 2, 1]In [76]: l[::-1]Out[76]: [1, 2, 3]