如何在 Python 中将字符串转换为有效的变量名？

Question

I need to convert an arbitrary string to a string that is a valid variable name in Python.

Here's a very basic example:

s1 = 'name/with/slashes'
s2 = 'name '

def clean(s):
    s = s.replace('/', '')
    s = s.strip()

    return s

# the _ is there so I can see the end of the string
print clean(s1) + '_'

That is a very naive approach. I need to check if the string contains invalid variable name characters and replace them with ''

What would be a pythonic way to do this?

Answer 1

Well, I'd like to best Triptych's solution with ... a one-liner!

>>> def clean(varStr): return re.sub('\W|^(?=\d)','_', varStr)
...

>>> clean('32v2 g #Gmw845h$W b53wi ')
'_32v2_g__Gmw845h_W_b53wi_'

This substitution replaces any non-variable appropriate character with underscore and inserts underscore in front if the string starts with a digit. IMO, 'name/with/slashes' looks better as variable name name_with_slashes than as namewithslashes .

Answer 2

According to Python , an identifier is a letter or underscore, followed by an unlimited string of letters, numbers, and underscores:

import re

def clean(s):

   # Remove invalid characters
   s = re.sub('[^0-9a-zA-Z_]', '', s)

   # Remove leading characters until we find a letter or underscore
   s = re.sub('^[^a-zA-Z_]+', '', s)

   return s

Use like this:

>>> clean(' 32v2 g #Gmw845h$W b53wi ')
'v2gGmw845hWb53wi'

Answer 3

您应该构建一个正则表达式，它是允许字符的白名单，并替换不在该字符类中的所有内容。

Answer 4

You can use the built in func: str.isidentifier() in combination with filter() . This requires no imports such as re and works by iterating over each character and returning it if its an identifier. Then you just do a ''.join to convert the array to a string again.

s1 = 'name/with/slashes'
s2 = 'name '

def clean(s):
    s = ''.join(filter(str.isidentifier, s))
    return s

print f'{clean(s1)}_' #the _ is there so I can see the end of the string

Answer 5

使用 re 模块，并去除所有无效字符。