s = 'abc'
t = s[-1::-1] #<<<==========
s[::-1]即可。
In [16]: %timeit 'woshiyitiaozifuchuan'[::-1]
1000000 loops, best of 3: 242 ns per loop
In [17]: %timeit 'woshiyitiaozifuchuan'[-1::-1]
1000000 loops, best of 3: 246 ns per loop
In [18]: %timeit reversed('woshiyitiaozifuchuan')
10000000 loops, best of 3: 173 ns per loop
In [1]: %timeit u'含敏感词组长字符串'[::-1
]
1000000 loops, best of 3: 1.53 us per loop
In [6]: %timeit u'含敏感词组长字符串'[::-1
1000000 loops, best of 3: 1.49 us per loop
In [2]: %timeit u'含敏感词组长字符串'[-1::
1000000 loops, best of 3: 1.48 us per loop
In [5]: %timeit u'含敏感词组长字符串'[-1::
-1]
1000000 loops, best of 3: 1.49 us per loop
In [3]: %timeit reversed(u'含敏感词组长字符串')
1000000 loops, best of 3: 321 ns per loop
In [4]: %timeit reversed(u'含敏感词组长字符串')
1000000 loops, best of 3: 322 ns per loop
In [50]: ua = ''.join(random.choice(u'天姥连天向天横 ') for _ in range(10000))
In [51]: len(ua)
Out[51]: 10000
In [52]: %timeit reversed(ua)
10000000 loops, best of 3: 112 ns per loop
In [53]: type(reversed(ua))
Out[53]: reversed
In [54]: len(letters)
Out[54]: 53
In [55]: %timeit reversed(letters)
10000000 loops, best of 3: 112 ns per loop
In [56]: reversed?
Type: type
String Form:<type 'reversed'>
Namespace: Python builtin
Docstring:
reversed(sequence) -> reverse iterator over values of the sequence
Return a reverse iterator
In [57]: l = [1,2,3]
In [58]: b = reversed(l)
In [59]: l[0] = 5
In [60]: list(b)
Out[60]: [3, 2, 5]
