我有一个这样的字符串:

this is "a test"

我试图在Python中写一些东西,通过空格分割它,同时忽略引号中的空格。我想要的结果是:

['this', 'is', 'a test']

PS,我知道你会问“如果引号中有引号会发生什么,在我的应用程序中,这永远不会发生。


当前回答

如果你不关心子字符串

>>> 'a short sized string with spaces '.split()

性能:

>>> s = " ('a short sized string with spaces '*100).split() "
>>> t = timeit.Timer(stmt=s)
>>> print "%.2f usec/pass" % (1000000 * t.timeit(number=100000)/100000)
171.39 usec/pass

或者字符串模块

>>> from string import split as stringsplit; 
>>> stringsplit('a short sized string with spaces '*100)

性能:String模块的性能似乎比字符串方法更好

>>> s = "stringsplit('a short sized string with spaces '*100)"
>>> t = timeit.Timer(s, "from string import split as stringsplit")
>>> print "%.2f usec/pass" % (1000000 * t.timeit(number=100000)/100000)
154.88 usec/pass

或者你可以使用RE引擎

>>> from re import split as resplit
>>> regex = '\s+'
>>> medstring = 'a short sized string with spaces '*100
>>> resplit(regex, medstring)

性能

>>> s = "resplit(regex, medstring)"
>>> t = timeit.Timer(s, "from re import split as resplit; regex='\s+'; medstring='a short sized string with spaces '*100")
>>> print "%.2f usec/pass" % (1000000 * t.timeit(number=100000)/100000)
540.21 usec/pass

对于非常长的字符串,您不应该将整个字符串加载到内存中,而是将行分开或使用迭代循环

其他回答

嗯,好像找不到“回复”按钮了…不管怎样,这个答案是基于Kate的方法,但正确地分割了包含转义引号的子字符串,并删除了子字符串的开始和结束引号:

  [i.strip('"').strip("'") for i in re.split(r'(\s+|(?<!\\)".*?(?<!\\)"|(?<!\\)\'.*?(?<!\\)\')', string) if i.strip()]

这适用于'这是' a \\\"test\\\"\\\'s子字符串' '这样的字符串(不幸的是,为了防止Python删除转义,这个疯狂的标记是必要的)。

如果返回列表中的字符串不需要转义,您可以使用稍微修改过的函数版本:

[i.strip('"').strip("'").decode('string_escape') for i in re.split(r'(\s+|(?<!\\)".*?(?<!\\)"|(?<!\\)\'.*?(?<!\\)\')', string) if i.strip()]

我看到这里的正则表达式方法看起来很复杂和/或错误。这让我很惊讶,因为正则表达式语法可以很容易地描述“空格或引号包围的东西”,而且大多数正则表达式引擎(包括Python的)都可以在正则表达式上进行拆分。所以如果你要使用正则表达式,为什么不直接说出你的意思呢?:

test = 'this is "a test"'  # or "this is 'a test'"
# pieces = [p for p in re.split("( |[\\\"'].*[\\\"'])", test) if p.strip()]
# From comments, use this:
pieces = [p for p in re.split("( |\\\".*?\\\"|'.*?')", test) if p.strip()]

解释:

[\\\"'] = double-quote or single-quote
.* = anything
( |X) = space or X
.strip() = remove space and empty-string separators

不过,Shlex可能提供更多的特性。

试试这个:

  def adamsplit(s):
    result = []
    inquotes = False
    for substring in s.split('"'):
      if not inquotes:
        result.extend(substring.split())
      else:
        result.append(substring)
      inquotes = not inquotes
    return result

一些测试字符串:

'This is "a test"' -> ['This', 'is', 'a test']
'"This is \'a test\'"' -> ["This is 'a test'"]

我建议:

测试字符串:

s = 'abc "ad" \'fg\' "kk\'rdt\'" zzz"34"zzz "" \'\''

也要捕捉""和":

import re
re.findall(r'"[^"]*"|\'[^\']*\'|[^"\'\s]+',s)

结果:

['abc', '"ad"', "'fg'", '"kk\'rdt\'"', 'zzz', '"34"', 'zzz', '""', "''"]

忽略空的""和":

import re
re.findall(r'"[^"]+"|\'[^\']+\'|[^"\'\s]+',s)

结果:

['abc', '"ad"', "'fg'", '"kk\'rdt\'"', 'zzz', '"34"', 'zzz']

根据你的用例,你可能还想检查csv模块:

import csv
lines = ['this is "a string"', 'and more "stuff"']
for row in csv.reader(lines, delimiter=" "):
    print(row)

输出:

['this', 'is', 'a string']
['and', 'more', 'stuff']