Error: bad escape in Python script with regex

Question

I am trying to do a search between lists and return the value when it matches, and when it does not.

import re

array = ['brasil','argentina','chile','canada']
array2 = ['brasil.sao_paulo','chile','argentina']

for x,y in zip(array,array2):
  if re.search('\\{}\\b'.format(x), y, re.IGNORECASE):
    print("Match: {}".format(x))
  else:
    print("Not match: {}".format(y))

Output:

Not match: brasil.sao_paulo
Not match: chile
Traceback (most recent call last):
  File "main.py", line 7, in <module>
    if re.search('\\{}\\b'.format(x), y, re.IGNORECASE):
  File "/usr/local/lib/python3.7/re.py", line 183, in search
re.error: bad escape \c at position 0

Desired output:

Match: brasil
Match: argentina
Match: chile
Not match: canada

The regex which fails is \chile\b. I imagine that is not what you wanted to search for. — zvone
– zvone, Commented Dec 18, 2019 at 20:13

David Remus · Accepted Answer · 2019-12-18 20:28:59Z

4

If I understand correctly, you don't need regex here.

group_1 = ['brasil','argentina','chile','canada']
group_2 = ['brasil.sao_paulo','chile','argentina']

for x in group_1:
    # For group 2 only, this picks out the part of the string that appears before the first ".".
  if x in [y.split('.')[0] for y in group_2]:
    print("Match: {}".format(x))
  else:
    print("Not match: {}".format(x))

which returns

Match: brasil
Match: argentina
Match: chile
Not match: canada

edited Dec 18, 2019 at 20:28

answered Dec 18, 2019 at 20:24

David Remus

564 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ggorlen · Accepted Answer · 2019-12-18 20:22:00Z

2

If you zip, you'll only get pairwise matches. Given the nature of your search, you can just join up the haystack into a space-delimited string and join needles into a pattern with alternation and let findall chug away:

>>> import re
>>> needles = ['brasil', 'argentina', 'chile', 'canada']
>>> haystack = ['brasil.sao_paulo', 'chile', 'argentina']
>>> re.findall(r"\b%s\b" % "|".join(needles), " ".join(haystack), re.I)
['brasil', 'chile', 'argentina']

The intent behind \\ in the original regex is unclear, so I assume you want \b on both sides of the pattern.

answered Dec 18, 2019 at 20:22

ggorlen

59.3k8 gold badges119 silver badges173 bronze badges

Comments

Michael Chatiskatzi · Accepted Answer · 2019-12-18 22:42:55Z

1

A simple solution with the any method:

array = ['brasil', 'argentina', 'chile', 'canada']
array2 = ['brasil.sao_paulo', 'chile', 'argentina']

for x in array:
    if any(x.casefold() in y.casefold() for y in array2):
        print("Match:", x)
    else:
        print("Not match:", x)

Try it online!

Edit: Using casefold() to make it case-insensitive.

edited Dec 18, 2019 at 22:42

answered Dec 18, 2019 at 21:00

Michael Chatiskatzi

2451 gold badge5 silver badges17 bronze badges

Collectives™ on Stack Overflow

Error: bad escape in Python script with regex

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related