使用Python从字符串中剥离所有非字母数字字符的最佳方法是什么?
在这个问题的PHP变体中提出的解决方案可能会进行一些小的调整，但对我来说似乎不太“python化”。
声明一下，我不只是想去掉句号和逗号(以及其他标点符号)，还想去掉引号、括号等。
当前回答
使用ASCII可打印文件的随机字符串计时:
from inspect import getsource
from random import sample
import re
from string import printable
from timeit import timeit
pattern_single = re.compile(r'[\W]')
pattern_repeat = re.compile(r'[\W]+')
translation_tb = str.maketrans('', '', ''.join(c for c in map(chr, range(256)) if not c.isalnum()))
def generate_test_string(length):
return ''.join(sample(printable, length))
def main():
for i in range(0, 60, 10):
for test in [
lambda: ''.join(c for c in generate_test_string(i) if c.isalnum()),
lambda: ''.join(filter(str.isalnum, generate_test_string(i))),
lambda: re.sub(r'[\W]', '', generate_test_string(i)),
lambda: re.sub(r'[\W]+', '', generate_test_string(i)),
lambda: pattern_single.sub('', generate_test_string(i)),
lambda: pattern_repeat.sub('', generate_test_string(i)),
lambda: generate_test_string(i).translate(translation_tb),
]:
print(timeit(test), i, getsource(test).lstrip(' lambda: ').rstrip(',\n'), sep='\t')
if __name__ == '__main__':
main()
结果(Python 3.7):
Time Length Code
6.3716264850008880 00 ''.join(c for c in generate_test_string(i) if c.isalnum())
5.7285426190064750 00 ''.join(filter(str.isalnum, generate_test_string(i)))
8.1875841680011940 00 re.sub(r'[\W]', '', generate_test_string(i))
8.0002205439959650 00 re.sub(r'[\W]+', '', generate_test_string(i))
5.5290945199958510 00 pattern_single.sub('', generate_test_string(i))
5.4417179649972240 00 pattern_repeat.sub('', generate_test_string(i))
4.6772285089973590 00 generate_test_string(i).translate(translation_tb)
23.574712151996210 10 ''.join(c for c in generate_test_string(i) if c.isalnum())
22.829975890002970 10 ''.join(filter(str.isalnum, generate_test_string(i)))
27.210196289997840 10 re.sub(r'[\W]', '', generate_test_string(i))
27.203713296003116 10 re.sub(r'[\W]+', '', generate_test_string(i))
24.008979928999906 10 pattern_single.sub('', generate_test_string(i))
23.945240008994006 10 pattern_repeat.sub('', generate_test_string(i))
21.830899796994345 10 generate_test_string(i).translate(translation_tb)
38.731336012999236 20 ''.join(c for c in generate_test_string(i) if c.isalnum())
37.942474347000825 20 ''.join(filter(str.isalnum, generate_test_string(i)))
42.169366310001350 20 re.sub(r'[\W]', '', generate_test_string(i))
41.933375883003464 20 re.sub(r'[\W]+', '', generate_test_string(i))
38.899814646996674 20 pattern_single.sub('', generate_test_string(i))
38.636144253003295 20 pattern_repeat.sub('', generate_test_string(i))
36.201238164998360 20 generate_test_string(i).translate(translation_tb)
49.377356811004574 30 ''.join(c for c in generate_test_string(i) if c.isalnum())
48.408927293996385 30 ''.join(filter(str.isalnum, generate_test_string(i)))
53.901889764994850 30 re.sub(r'[\W]', '', generate_test_string(i))
52.130339455994545 30 re.sub(r'[\W]+', '', generate_test_string(i))
50.061149017004940 30 pattern_single.sub('', generate_test_string(i))
49.366573111998150 30 pattern_repeat.sub('', generate_test_string(i))
46.649754120997386 30 generate_test_string(i).translate(translation_tb)
63.107938601999194 40 ''.join(c for c in generate_test_string(i) if c.isalnum())
65.116287978999030 40 ''.join(filter(str.isalnum, generate_test_string(i)))
71.477421126997800 40 re.sub(r'[\W]', '', generate_test_string(i))
66.027950693998720 40 re.sub(r'[\W]+', '', generate_test_string(i))
63.315361931003280 40 pattern_single.sub('', generate_test_string(i))
62.342320287003530 40 pattern_repeat.sub('', generate_test_string(i))
58.249303059004890 40 generate_test_string(i).translate(translation_tb)
73.810345625002810 50 ''.join(c for c in generate_test_string(i) if c.isalnum())
72.593953348005020 50 ''.join(filter(str.isalnum, generate_test_string(i)))
76.048324580995540 50 re.sub(r'[\W]', '', generate_test_string(i))
75.106637657001560 50 re.sub(r'[\W]+', '', generate_test_string(i))
74.681338128997600 50 pattern_single.sub('', generate_test_string(i))
72.430461594005460 50 pattern_repeat.sub('', generate_test_string(i))
69.394243567003290 50 generate_test_string(i).translate(translation_tb)
str.maketrans & str.translate是最快的，但包括所有非ascii字符。 重新编译&模式。Sub较慢，但不知何故比"快。加入&过滤。
其他回答
使用ASCII可打印文件的随机字符串计时:
from inspect import getsource
from random import sample
import re
from string import printable
from timeit import timeit
pattern_single = re.compile(r'[\W]')
pattern_repeat = re.compile(r'[\W]+')
translation_tb = str.maketrans('', '', ''.join(c for c in map(chr, range(256)) if not c.isalnum()))
def generate_test_string(length):
return ''.join(sample(printable, length))
def main():
for i in range(0, 60, 10):
for test in [
lambda: ''.join(c for c in generate_test_string(i) if c.isalnum()),
lambda: ''.join(filter(str.isalnum, generate_test_string(i))),
lambda: re.sub(r'[\W]', '', generate_test_string(i)),
lambda: re.sub(r'[\W]+', '', generate_test_string(i)),
lambda: pattern_single.sub('', generate_test_string(i)),
lambda: pattern_repeat.sub('', generate_test_string(i)),
lambda: generate_test_string(i).translate(translation_tb),
]:
print(timeit(test), i, getsource(test).lstrip(' lambda: ').rstrip(',\n'), sep='\t')
if __name__ == '__main__':
main()
结果(Python 3.7):
Time Length Code
6.3716264850008880 00 ''.join(c for c in generate_test_string(i) if c.isalnum())
5.7285426190064750 00 ''.join(filter(str.isalnum, generate_test_string(i)))
8.1875841680011940 00 re.sub(r'[\W]', '', generate_test_string(i))
8.0002205439959650 00 re.sub(r'[\W]+', '', generate_test_string(i))
5.5290945199958510 00 pattern_single.sub('', generate_test_string(i))
5.4417179649972240 00 pattern_repeat.sub('', generate_test_string(i))
4.6772285089973590 00 generate_test_string(i).translate(translation_tb)
23.574712151996210 10 ''.join(c for c in generate_test_string(i) if c.isalnum())
22.829975890002970 10 ''.join(filter(str.isalnum, generate_test_string(i)))
27.210196289997840 10 re.sub(r'[\W]', '', generate_test_string(i))
27.203713296003116 10 re.sub(r'[\W]+', '', generate_test_string(i))
24.008979928999906 10 pattern_single.sub('', generate_test_string(i))
23.945240008994006 10 pattern_repeat.sub('', generate_test_string(i))
21.830899796994345 10 generate_test_string(i).translate(translation_tb)
38.731336012999236 20 ''.join(c for c in generate_test_string(i) if c.isalnum())
37.942474347000825 20 ''.join(filter(str.isalnum, generate_test_string(i)))
42.169366310001350 20 re.sub(r'[\W]', '', generate_test_string(i))
41.933375883003464 20 re.sub(r'[\W]+', '', generate_test_string(i))
38.899814646996674 20 pattern_single.sub('', generate_test_string(i))
38.636144253003295 20 pattern_repeat.sub('', generate_test_string(i))
36.201238164998360 20 generate_test_string(i).translate(translation_tb)
49.377356811004574 30 ''.join(c for c in generate_test_string(i) if c.isalnum())
48.408927293996385 30 ''.join(filter(str.isalnum, generate_test_string(i)))
53.901889764994850 30 re.sub(r'[\W]', '', generate_test_string(i))
52.130339455994545 30 re.sub(r'[\W]+', '', generate_test_string(i))
50.061149017004940 30 pattern_single.sub('', generate_test_string(i))
49.366573111998150 30 pattern_repeat.sub('', generate_test_string(i))
46.649754120997386 30 generate_test_string(i).translate(translation_tb)
63.107938601999194 40 ''.join(c for c in generate_test_string(i) if c.isalnum())
65.116287978999030 40 ''.join(filter(str.isalnum, generate_test_string(i)))
71.477421126997800 40 re.sub(r'[\W]', '', generate_test_string(i))
66.027950693998720 40 re.sub(r'[\W]+', '', generate_test_string(i))
63.315361931003280 40 pattern_single.sub('', generate_test_string(i))
62.342320287003530 40 pattern_repeat.sub('', generate_test_string(i))
58.249303059004890 40 generate_test_string(i).translate(translation_tb)
73.810345625002810 50 ''.join(c for c in generate_test_string(i) if c.isalnum())
72.593953348005020 50 ''.join(filter(str.isalnum, generate_test_string(i)))
76.048324580995540 50 re.sub(r'[\W]', '', generate_test_string(i))
75.106637657001560 50 re.sub(r'[\W]+', '', generate_test_string(i))
74.681338128997600 50 pattern_single.sub('', generate_test_string(i))
72.430461594005460 50 pattern_repeat.sub('', generate_test_string(i))
69.394243567003290 50 generate_test_string(i).translate(translation_tb)
str.maketrans & str.translate是最快的，但包括所有非ascii字符。 重新编译&模式。Sub较慢，但不知何故比"快。加入&过滤。
>>> import re
>>> string = "Kl13@£$%[};'\""
>>> pattern = re.compile('\W')
>>> string = re.sub(pattern, '', string)
>>> print string
Kl13
如何:
def ExtractAlphanumeric(InputString):
from string import ascii_letters, digits
return "".join([ch for ch in InputString if ch in (ascii_letters + digits)])
如果InputString中的字符存在于ascii_letters和digits的组合字符串中，则可以使用列表推导来生成InputString中的字符列表。然后它将列表连接在一起，形成一个字符串。
正则表达式的拯救:
import re
re.sub(r'\W+', '', your_string)
根据Python定义'\W == [^a-zA-Z0-9_]，它不包括所有数字、字母和_
Python 3
使用与@John Machin的答案相同的方法，但针对Python 3进行了更新:
更大的字符集 对翻译工作方式的轻微改变。
现在假定Python代码是用UTF-8编码的 (来源:PEP 3120)
这意味着包含你想要删除的所有字符的字符串会变得更大:
del_chars = ''.join(c for c in map(chr, range(1114111)) if not c.isalnum())
翻译方法现在需要使用一个翻译表，我们可以用maketrans()创建:
del_map = str.maketrans('', '', del_chars)
现在，像以前一样，任何你想要“捏碎”的字符串:
scrunched = s.translate(del_map)
使用来自@Joe Machin的最后一个计时例子，我们可以看到它仍然比re强一个数量级:
> python -mtimeit -s"d=''.join(c for c in map(chr,range(1114111)) if not c.isalnum());m=str.maketrans('','',d);s='foo-'*25" "s.translate(m)"
1000000 loops, best of 5: 255 nsec per loop
> python -mtimeit -s"import re;s='foo-'*25;r=re.compile(r'[\W_]+')" "r.sub('',s)"
50000 loops, best of 5: 4.8 usec per loop
推荐文章
- 将一个列表分成大约相等长度的N个部分
- Python __str__与__unicode__
- 在python中，del和delattr哪个更好?
- 如何动态加载Python类
- 有没有办法在python中做HTTP PUT
- “foo Is None”和“foo == None”之间有什么区别吗?
- 类没有对象成员
- Django模型“没有显式声明app_label”
- bash:错误的替换
- 熊猫能自动从CSV文件中读取日期吗?
- 在python中zip的逆函数是什么?
- 有效的方法应用多个过滤器的熊猫数据框架或系列
- 在c#中检查字符串是否只包含数字的最快方法
- 如何检索插入id后插入行在SQLite使用Python?
- 我如何在Django中添加一个CharField占位符?
