Regex will not sub characters '\\'

Question

I want to remove the characters \\ from my string. I have tried regextester and it matches, https://regex101.com/r/euGZsQ/1

 s = '''That\\'s not true. There are a range of causes. There are a        range of issues that we have to address. First of all, we have to identify, share and accept that there is a problem and that we\\''''

 pattern = re.compile(r'\\{2,}')
 re.sub(pattern, '', s)

I would expect the sub method to replace my \\ with nothing to clean up my string.

if only wants to remove '\\' why don't you replace it? s.replace("\\\\", "") — Siyavash vaez afshar, Jun 10 '19 at 06:43

score 4 · Accepted Answer · answered Jun 10 '19 at 06:42

4

The problem is that your string itself is not marked as a raw string. Therefore, the first \ actually escapes the second.

Observe:

import re

pattern = re.compile(r'\\{2,}')
s = r'''That\\'s not true. There are a range of causes. There are a        range of issues that we have to address. First of all, we have to identify, share and accept that there is a problem and that we\\'''
re.sub(pattern, '', s)

Output:

"That's not true. There are a range of causes. There are a        range of issues that we have to address. First of all, we have to identify, share and accept that there is a problem and that we"

answered Jun 10 '19 at 06:42

gmds

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Great it works, will accept when available. However, my actual use case is a string converted from a list with `s = r' '.join(s)`. Converting to a raw string does not solve this problem. – frantic oreo Jun 10 '19 at 06:52
1

@franticoreo How do you know that your string in fact has two backslashes? Note that each backslash will be printed twice. Try removing `{2,}` from the regex or just using `.replace('\\', '')`. – gmds Jun 10 '19 at 06:53
1

@franticoreo Note also that `r''.join(...)` is the same as `''.join(...)`. "raw string" only has meaning as a *literal*. – gmds Jun 10 '19 at 06:59

score 0 · Answer 2 · answered Jun 10 '19 at 06:44

You can try:

import re
s = '''That\\'s not true. There are a range of causes. There are a        range of issues that we have to address. First of all, we have to identify, share and accept that there is a problem and that we\\' '''
d = re.sub(r'\\', '', s)
print(d)

Output :

That's not true. There are a range of causes. There are a        range of issues that we have to address. First of all
, we have to identify, share and accept that there is a problem and that we'

Note that this would match a single backslash too. – gmds Jun 10 '19 at 06:47 — gmds, Jun 10 '19 at 06:47

Regex will not sub characters '\\'

2 Answers2