将字符串中的字母与给定数量的同级字母组合起来

Question

对于给定的字符串，我只需要将单词的字符与一定数量的同级组合，即Hello与3，组合将是：Hel，ell，llo

a试图使用组合和置换函数，但我无法控制该函数如何组合字符

Answer 1

您只需遍历字符串索引，忽略长度过短的最后两个索引

>>> foo = 'hello'
>>> [foo[i:i+3] for i, _ in enumerate(foo) if i+2 < len(foo)]
['hel', 'ell', 'llo']

Answer 2

>>> def substrings(s, length=3):
...     yield from (s[i:i + length] for i in range(len(s) - length + 1))
...
>>>
>>> list(substrings("Hello"))
['Hel', 'ell', 'llo']
>>> list(substrings("Hello", length=2))
['He', 'el', 'll', 'lo']
>>> list(substrings("Hello", length=5))
['Hello']
>>> list(substrings("Hello", length=6))
[]