Develop Reference

How do I use re to obtain multiple variables with similar formatting?

I am trying to obtain strings with similar pattern multiple times.
For example, for my string "SeNetworkLogonRight = *S-1-5-11,*S-1-5-32-544", I am trying to obtain "*S-1-5-11" and "*S-1-5-32-544" and append them to a list. I tried doing the following:
>>> test = "SeNetworkLogonRight = *S-1-5-11,*S-1-5-32-544"
>>> print(re.findall('[*].[^.]*\d$', test))
Result obtained:
['*S-1-5-11,*S-1-5-32-544']
How do I obtain the values separately and append it into a list in such a format?
['*S-1-5-11', '*S-1-5-32-544']

You may match an asterisk and any 1+ chars other than commas after:
r'\*[^,]+'
Details
\* - an asterisk (must be escaped as it is a special regex metacharacter otherwise)
[^,]+ - a negated character class matching 1 or more chars other than comma.
Python demo:
import re
test = "SeNetworkLogonRight = *S-1-5-11,*S-1-5-32-544"
print(re.findall(r'\*[^,]+', test))
# => ['*S-1-5-11', '*S-1-5-32-544']

Do not match if word appears in regex

I have a url, and I want it to NOT match if the word 'season' is contained in the url. Here are two examples:
CONTAINS SEASON, DO NOT MATCH
'http://imdb.com/title/tt0285331/episodes?this=1&season=7&ref_=tt_eps_sn_7'
DOES NOT CONTAIN SEASON, MATCH
'http://imdb.com/title/tt0285331/
Here is what I have so far, but I'm afraid the .+ will match everything until the end. What would be the correct regex to use here?
r'http://imdb.com/title/tt(\d)+/.+^[season].+'

Use a negative lookahead:
urls='''\
http://imdb.com/title/tt0285331/episodes?this=1&season=7&ref_=tt_eps_sn_7
http://imdb.com/title/tt0285331/'''
import re
print re.findall(r'^(?!.*\bseason\b)(.*)', urls, re.M)
# ['http://imdb.com/title/tt0285331/']

You cannot use whole words inside of character classes, you have to use a Negative Lookahead.
>>> s = '''
http://imdb.com/title/tt0285331/episodes?this=1&season=7&ref_=tt_eps_sn_7
http://imdb.com/title/tt0285331/
http://imdb.com/title/tt1111111/episodes?this=2
http://imdb.com/title/tt0123456/episodes?this=1&season=1&ref_=tt_eps_sn_1'''
>>> import re
>>> re.findall(r'\bhttp://imdb.com/title/tt(?!\S+\bseason)\S+', s)
# ['http://imdb.com/title/tt0285331/', 'http://imdb.com/title/tt0285331/episodes?this=2']

Use a negative lokahead just after to tt\d+/,
>>> import re
>>> s = """http://imdb.com/title/tt0285331/episodes?this=1&season=7&ref_=tt_eps_sn_7
... http://imdb.com/title/tt0285331/
... """
>>> m = re.findall(r'^http://imdb.com/title/tt\d+/(?:(?!season).)*$', s, re.M)
>>> for i in m:
... print i
...
http://imdb.com/title/tt0285331/

python 3 regular expression match string meta-character

I want to write a line of regular expression that can match strings like "(2000)" with years in parentheses. then I can check if any string contains the substring "2000".
for example, I want the regex to match (2000) not 2000, or (20000),or (200).
That is to say: they have to have exactly four digits, the first digit between 1 and 2; they have to include the parentheses.
also 2000 is just an example I use but really I want to the regex to include all the possible years.

You have to escape the open and close paranthesis,
>>> import re
>>> str = """foo(2000)bar(1000)foobar2000"""
>>> regex = r'\(2000\)'
>>> result = re.findall(regex, str)
>>> print(result)
['(2000)']
OR
>>> import re
>>> str = """foo(2000)bar(1000)foobar(2014)barfoo(2020)"""
>>> regex = r'\([0-9]{4}\)'
>>> result = re.findall(regex, str)
>>> print(result)
['(2000)', '(1000)', '(2014)', '(2020)']
It matches all the four digit numbers(year's) present within the paranthesis.

Special characters need to be escaped with a backslash. A parenthesis ( becomes \(. Therefore (2000) becomes \(2000\).
Then you can do something like:
if re.search(r"\(2000\)", subject):
# Successful match
else:
# Match attempt failed

>>> import re
>>> x = re.match(r'\((\d*?)\)', "(2000)")
>>> x.group(1)
'2000'

How do I extract certain parts of strings in Python?

Say I have three strings:
abc534loif
tvd645kgjf
tv96fjbd_gfgf
and three lists:
beginning captures just the first part of the string "the name"
middle captures just the number
end contains only the rest of the characters that are after the number portion
How do I accomplish this in the most efficent way?

Use regular expressions?
>>> import re
>>> strings = 'abc534loif tvd645kgjf tv96fjbd_gfgf'.split()
>>> for s in strings:
... for match in re.finditer(r'\b([a-z]+)(\d+)(.+?)\b', s):
... print match.groups()
...
('abc', '534', 'loif')
('tvd', '645', 'kgjf')
('tv', '96', 'fjbd_gfgf')

This is language agnostic approach that aims at higher efficiency:
find first digit in the string and save its position p0
find last digit in the string and save its position p1
extract substring from 0 to p0-1 into beginning
extract substring from p0 to p1 into middle
extract substring from p1+1 to length-1 into end

I guess you're looking for re.findall:
strs = """
abc534loif
tvd645kgjf
tv96fjbd_gfgf
"""
import re
print re.findall(r'\b(\w+?)(\d+)(\w+)', strs)
>> [('abc', '534', 'loif'), ('tvd', '645', 'kgjf'), ('tv', '96', 'fjbd_gfgf')]

>>> import itertools as it
>>> s="abc534loif"
>>> [''.join(j) for i,j in it.groupby(s, key=str.isdigit)]
['abc', '534', 'loif']

I'd something like this:
>>> import re
>>> l = ['abc534loif', 'tvd645kgjf', 'tv96fjbd_gfgf']
>>> regex = re.compile('([a-z_]+)(\d+)([a-z_]+)')
>>> beginning, middle, end = zip(*[regex.match(s).groups() for s in l])
>>> beginning
('abc', 'tvd', 'tv')
>>> middle
('534', '645', '96')
>>> end
('loif', 'kgjf', 'fjbd_gfgf')

I wouls use regualar expressions like:
(?P<beginning>[^0-9]*)(?P<middle>[^0-9]*)(?P<end>[^0-9]*)
and pull out the three matching sections.
import re
m = re.match(r"(?P<beginning>[^0-9]*)(?P<middle>[^0-9]*)(?P<end>[^0-9]*)", "abc534loif")
m.group('beginning')
m.group('middle')
m.group('end')

import re #You want to match a string against a pattern so you import the regular expressions module 're'
mystring = "abc1234def" #Just a string to test with
match = re.match(r"^(\D+)([0)9]+](\D+)$") #Our regular expression. Everything between brackets is 'captured', meaning that it is accessible as one of the 'groups' in the returned match object. The ^ sign matches at the beginning of a string, while the $ matches the end. the characters in between the square brackets [0-9] are character ranges, so [0-9] matches any digit character, \D is any non-digit character.
if match: # match will be None if the string didn't match the pattern, so we need to check for that, as None.group doesn't exist.
beginning = match.group(1)
middle = match.group(2)
end = match.group(3)

How to substitute chars using unicode regex range

I am trying to remove chars from an unicode string. I have a whitelist of allowed unicode chars and I would like to remove everything that is not on the list.
allowed_list = ur'[\u0041-\u005A]|[\u0061-\u007A]|[\u00C0-\u00D6]|[\u00D8-\u00F6]|[\u00F8-\u012F]|\u0131|[\u0386]|[\u0388-\u038A]'
negated_list = ur'[^\u0041-\u005A]|[^\u0061-\u007A]|[^\u00C0-\u00D6]|[^\u00D8-\u00F6]|[^\u00F8-\u012F]|^\u0131|[^\u0386]|[^\u0388-\u038A]'
I am testing it with a subset of my list and I don't get why it is not working.
This removes all but lowercase latin chars:
>>> mystr = 'Arugg^]T'
>>> myre = re.compile(ur'[^\u0061-\u007A]', re.UNICODE)
>>> result = myre.sub('', mystr)
>>> result
'rugg'
This removes all but uppercase latin chars:
>>> mystr = 'Arugg^]T'
>>> myre = re.compile(ur'[^\u0041-\u005A]', re.UNICODE)
>>> result = myre.sub('', mystr)
>>> result
'AT'
But when I combine them, all chars get removed:
>>> mystr = 'Arugg^]T'
>>> myre = re.compile(ur'[^\u0041-\u005A]|[^\u0061-\u007A]', re.UNICODE)
>>> result = myre.sub('', mystr)
>>> result
''
When I tested the regex [^\u0041-\u005A]|[^\u0061-\u007A] on https://pythex.org/ it does what I am expecting, but when I atempt to use it in my code, it is not doing what I want it to. What am I missing?
Thank you in advance!

Your regex is not correct, you are using | which checks if either one is true.
You need to create one expression with multiple ranges,
[^\u0041-\u005A\u0061-\u007A] will match any characters except range \u0041-\u005A or \u0061-\u007A.
import re
regex = r"[^\u0041-\u005A\u0061-\u007A]"
test_str = "Arugg^]T"
myre = re.compile(regex, re.UNICODE)
result = myre.sub('', test_str)
print(result)
# output,
AruggT

Implicitly positive, regex class items are OR'd together.
Your regex is then the same as
[\u0041-\u005a\u0061-\u007a\u00c0-\u00d6\u00d8-\u00f6\u00f8-\u012f\u0131\u0386\u0388-\u038a]
But for the Negative regex class [^], items are individually negated then AND'ed together.
That regex is then
[^\u0041-\u005a\u0061-\u007a\u00c0-\u00d6\u00d8-\u00f6\u00f8-\u012f\u0131\u0386\u0388-\u038a]
which is logically the same as
[^\u0041-\u005A] and [^\u0061-\u007A] and [^\u00C0-\u00D6] and [^\u00D8-\u00F6] and [^\u00F8-\u012F] and [^\u0131] and [^\u0386] and [^\u0388-\u038A]
What you tried to do was negate each item, then OR them together
which is not the same.

You are replacing all characters that are
not in '[^\u0041-\u005A]' or not in [^\u0061-\u007A]' (due to the ^) .
If either one is true, all get replaced by '' - so its always true no matter what you have.
Use ur'[^\u0041-\u005A\u0061-\u007A]' instead (both ranges inside one [...].