re.sub does not replace a very simple regex

Question

I am trying to make a very simple regex replacement. Multiple others similar to this one work, but not this one.

I want every occurrence of either "/\" or "JI" character sequences to be replaced with "X". So, "/\JI" must turn into "XX".

However, here's what happens:

>>> import re
>>> phrase = '/\JI'
>>> phrase = re.sub('\/\\|JI', 'X', phrase)
>>> phrase
'/\\JI'

Why does it not detect either of the combinations and adds that second slash? regex101.com shows 2 full matches with the same string and same regex.

For detailed info https://stackoverflow.com/questions/10585349/python-how-to-replace-backslash-with-re-sub — Gunesh Shanbhag, May 18 '20 at 21:33
You should be using [raw strings](https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals) to make sure your backslashes are not interpreted as escape characters. — 0x5453, May 18 '20 at 21:34
Does this answer your question? [Python how to replace backslash with re.sub()](https://stackoverflow.com/questions/10585349/python-how-to-replace-backslash-with-re-sub) — Gunesh Shanbhag, May 18 '20 at 21:34
@GuneshShanbhag not really. That's a different question. I know how escaping and double escaping work. Still, thank you for your effort. — Andy Mac, May 18 '20 at 21:43

Tomás Denis Reyes Sánchez · Accepted Answer · 2020-05-18T21:36:59.037

1

Use re.sub(r'/\\|JI', 'X', phrase). Note the r before the string indicating raw.

edited May 18 '20 at 21:36

answered May 18 '20 at 21:33

1 Answers1