从字符串列表创建新的子字符串列表

Question

Is there an easy way in python of creating a list of substrings from a list of strings?

Example:

original list: ['abcd','efgh','ijkl','mnop']

list of substrings: ['bc','fg','jk','no']

I know this could be achieved with a simple loop but is there an easier way in python (Maybe a one-liner)?

Answer 1

Use slicing and list comprehension :

>>> lis = ['abcd','efgh','ijkl','mnop']
>>> [ x[1:3] for x in lis]
['bc', 'fg', 'jk', 'no']

Slicing:

>>> s = 'abcd'
>>> s[1:3]      #return sub-string from 1 to 2th index (3 in not inclusive)
'bc'

Answer 2

With a mix of slicing and list comprehensions you can do it like this

listy = ['abcd','efgh','ijkl','mnop']
[item[1:3] for item in listy]
>> ['bc', 'fg', 'jk', 'no']

Answer 3

You can use a one-liner list-comprehension .

Using slicing , and relative positions, you can then trim the first and last character in each item.

>>> l = ['abcd','efgh','ijkl','mnop']
>>> [x[1:-1] for x in l]
['bc', 'fg', 'jk', 'no']

If you are doing this many times, consider using a function:

def trim(string, trim_left=1, trim_right=1):
    return string[trim_left:-trim_right]

def trim_list(lst, trim_left=1, trim_right=1):
    return [trim(x, trim_left, trim_right) for x in lst] 

>>> trim_list(['abcd','efgh','ijkl','mnop'])
['bc', 'fg', 'jk', 'no']

Answer 4

如果你想在一行中做到这一点，你可以试试这个：

>>> map(lambda s: s[1:-1], ['abcd','efgh','ijkl','mnop'])