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replaceAll() method. A common solution to remove all non-alphanumeric characters from a String is with regular expressions. The idea is to use the regular expression [^A-Za-z0-9] to retain only alphanumeric characters in the string. You can also use [^\w] regular expression, which is equivalent to [^a-zA-Z_0-9] .
Using Regular Expression We can use the regular expression [^a-zA-Z0-9] to identify non-alphanumeric characters in a string. Replace the regular expression [^a-zA-Z0-9] with [^a-zA-Z0-9 _] to allow spaces and underscore character.
The approach is to use the String. replaceAll method to replace all the non-alphanumeric characters with an empty string.
Short example re. sub(r'\W+', '_', 'bla: bla**(bla)') replaces one or more consecutive non-alphanumeric characters by an underscore.
Regex to the rescue!
import re
s = re.sub('[^0-9a-zA-Z]+', '*', s)
Example:
>>> re.sub('[^0-9a-zA-Z]+', '*', 'h^&ell`.,|o w]{+orld')
'h*ell*o*w*orld'
The pythonic way.
print "".join([ c if c.isalnum() else "*" for c in s ])
This doesn't deal with grouping multiple consecutive non-matching characters though, i.e.
"h^&i => "h**i not "h*i" as in the regex solutions.
Try:
s = filter(str.isalnum, s)
in Python3:
s = ''.join(filter(str.isalnum, s))
Edit: realized that the OP wants to replace non-chars with '*'. My answer does not fit
Use \W which is equivalent to [^a-zA-Z0-9_]. Check the documentation, https://docs.python.org/2/library/re.html
import re
s = 'h^&ell`.,|o w]{+orld'
replaced_string = re.sub(r'\W+', '*', s)
output: 'h*ell*o*w*orld'
update: This solution will exclude underscore as well. If you want only alphabets and numbers to be excluded, then solution by nneonneo is more appropriate.
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