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to find the pattern using regex?

curP = "https://programmers.co.kr/learn/courses/4673'>#!Muzi#Muzi!)jayg07con&&"
I want to find the Muzi from this string with regex
for example
MuziMuzi : count 0 because it considers as one word
Muzi&Muzi: count 2 because it has & between so it separate the word
7Muzi7Muzi : count 2
I try to use the regex to find all matched
curP = "<a href='https://programmers.co.kr/learn/courses/4673'></a>#!Muzi#Muzi!)jayg07con&&"
pattern = re.compile('[^a-zA-Z]muzi[^a-zA-Z]')
print(pattern.findall(curP))
I expected the ['!muzi#','#Muzi!']
but the result is
['!muzi#']

You need to use this as your regex:
pattern = re.compile('[^a-zA-Z]muzi(?=[^a-zA-Z])', flags=re.IGNORECASE)
(?=[^a-zA-Z]) says that muzi must have a looahead of [^a-zA-Z] but does not consume any characters. So the first match is only matching !Muzi leaving the following # available to start the next match.
Your original regex was consuming !Muzi# leaving Muzi!, which would not match the regex.
Your matches will now be:
['!Muzi', '#Muzi']

As I understand it you want to get any value that may appear on both sides of your keyword Muzi.
That means that the #, in this case, has to be shared by both output values.
The only way to do it using regex is to manipulate the string as you find patterns.
Here is my solution:
import re
# Define the function to find the pattern
def find_pattern(curP):
pattern = re.compile('([^a-zA-Z]muzi[^a-zA-Z])', flags=re.IGNORECASE)
return pattern.findall(curP)[0]
curP = "<a href='https://programmers.co.kr/learn/courses/4673'></a>#!Muzi#Muzi!)jayg07con&&"
pattern_array = []
# Find the the first appearence of pattern on the string
pattern_array.append(find_pattern(curP))
# Remove the pattern found from the string
curP = curP.replace('Muzi','',1)
#Find the the second appearence of pattern on the string
pattern_array.append(find_pattern(curP))
print(pattern_array)
Output:
['!Muzi#', '#Muzi!']

How to match and replace this pattern in Python RE?

s = "[abc]abx[abc]b"
s = re.sub("\[([^\]]*)\]a", "ABC", s)
'ABCbx[abc]b'
In the string, s, I want to match 'abc' when it's enclosed in [], and followed by a 'a'. So in that string, the first [abc] will be replaced, and the second won't.
I wrote the pattern above, it matches:
match anything starting with a '[', followed by any number of characters which is not ']', then followed by the character 'a'.
However, in the replacement, I want the string to be like:
[ABC]abx[abc]b . // NOT ABCbx[abc]b
Namely, I don't want the whole matched pattern to be replaced, but only anything with the bracket []. How to achieve that?
match.group(1) will return the content in []. But how to take advantage of this in re.sub?

Why not simply include [ and ] in the substitution?
s = re.sub("\[([^\]]*)\]a", "[ABC]a", s)

There exist more than 1 method, one of them is exploting groups.
import re
s = "[abc]abx[abc]b"
out = re.sub('(\[)([^\]]*)(\]a)', r'\1ABC\3', s)
print(out)
Output:
[ABC]abx[abc]b
Note that there are 3 groups (enclosed in brackets) in first argument of re.sub, then I refer to 1st and 3rd (note indexing starts at 1) so they remain unchanged, instead of 2nd group I put ABC. Second argument of re.sub is raw string, so I do not need to escape \.

This regex uses lookarounds for the prefix/suffix assertions, so that the match text itself is only "abc":
(?<=\[)[^]]*(?=\]a)
Example: https://regex101.com/r/NDlhZf/1
So that's:
(?<=\[) - positive look-behind, asserting that a literal [ is directly before the start of the match
[^]]* - any number of non-] characters (the actual match)
(?=\]a) - positive look-ahead, asserting that the text ]a directly follows the match text.

RegEx for capturing and replacing digits in a pattern

I would like to replace the 3rd argument in the string with a new number (let's say 100). The matched string always starts with function, with the first argument either true or false, and with the number as second argument.
Expected
| |
v v
'function(true, 0, 15)' --> 'function(true, 0, 100)'
'function(false, 0, 23)' --> 'function(false, 0, 100)'
I have been reading the related posts but I believe I must have misunderstood some regex concept. The following code is that I had tried but it always replaces the whole string:
import re
string = 'function(true, 0, 15)'
regex = re.compile('function\([a-zA-Z]*, [0-9]*, ([0-9]*)\)')
res = re.sub(regex, '100', string)
print(res) # 100
# Expected: function(true, 0, 100)
Question: Could you point me out why the above code doesn't work? How would I write the code to achieve the expected result?

As the number you are trying to replace is just followed by a closing parenthesis ), you can just use this \d+(?=\s*\)) regex and replace it by 100 or whatever value you want. Try these Python codes,
import re
string = 'function(true, 0, 15)'
regex = re.compile(r'\d+(?=\s*\))')
res = re.sub(regex, '100', string)
print(res)
Prints,
function(true, 0, 100)
Also, the reason why your code isn't working as expected and is replacing whole of your string with 100 because the way you've written your regex, it matches your whole input and re.sub function replaces what all matches with second argument and hence all your input gets replaced with 100. But instead what you want is, to just replace the third argument with 100 hence the way you should write your regex, should only match the third argument value, like demonstrated in below regex demo,
Regex Demo matching only what you want to replace
And your current regex matches whole of your input as shown in below demo,
Regex Demo with your regex matching whole input
Also, in case you feel better and you want to match whole input and then selectively replace only third argument, you can use this regex to capture the function name and first two parameters in group1 like you wanted to capture in your original regex,
(function\([a-zA-Z]*, [0-9]*, )[0-9]*\)
and replace it with \g<1>100) where \g<1> references the value captured in group1 and further it is replaced with 100)
Regex Demo with full match and selected replacement

This expression also might work:
(?:\d+)(\))
which has a non-capturing group with our desired digits (?:\d+), followed by a right boundary (\)), which we can replace it with our new number and $1.
Test
# coding=utf8
# the above tag defines encoding for this document and is for Python 2.x compatibility
import re
regex = r"(?:\d+)(\))"
test_str = "function(true, 0, 15)"
subst = "100\\1"
# You can manually specify the number of replacements by changing the 4th argument
result = re.sub(regex, subst, test_str, 0, re.MULTILINE)
if result:
print (result)
# Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.
Demo

An alternative, you can print everything before the match and everything after the match, then print it out with the new result like so:
regex = re.compile( '(function\([a-zA-Z]*, [0-9]*, )([0-9]*)(\))' )
res = re.sub( regex, r'\1 100\3', string )
Basically, I placed parenthesis around the text before the expected match and after the expected match. Then I print it out as \1 (first match) 100 (new text) \3 (third match).
The reason why I propose this particular expression is in case OP specifically needs to only match strings that also contain the preceding "function(" section (or some other pattern). Plus, this is just an extension of OP's solution, so it may be more intuitive to OP.

Python regex to match after the text and the dot [duplicate]

I am using Python and would like to match all the words after test till a period (full-stop) or space is encountered.
text = "test : match this."
At the moment, I am using :
import re
re.match('(?<=test :).*',text)
The above code doesn't match anything. I need match this as my output.

Everything after test, including test
test.*
Everything after test, without test
(?<=test).*
Example here on regexr.com

You need to use re.search since re.match tries to match from the beging of the string. To match until a space or period is encountered.
re.search(r'(?<=test :)[^.\s]*',text)
To match all the chars until a period is encountered,
re.search(r'(?<=test :)[^.]*',text)

In a general case, as the title mentions, you may capture with (.*) pattern any 0 or more chars other than newline after any pattern(s) you want:
import re
p = re.compile(r'test\s*:\s*(.*)')
s = "test : match this."
m = p.search(s) # Run a regex search anywhere inside a string
if m: # If there is a match
print(m.group(1)) # Print Group 1 value
If you want . to match across multiple lines, compile the regex with re.DOTALL or re.S flag (or add (?s) before the pattern):
p = re.compile(r'test\s*:\s*(.*)', re.DOTALL)
p = re.compile(r'(?s)test\s*:\s*(.*)')
However, it will retrun match this.. See also a regex demo.
You can add \. pattern after (.*) to make the regex engine stop before the last . on that line:
test\s*:\s*(.*)\.
Watch out for re.match() since it will only look for a match at the beginning of the string (Avinash aleady pointed that out, but it is a very important note!)
See the regex demo and a sample Python code snippet:
import re
p = re.compile(r'test\s*:\s*(.*)\.')
s = "test : match this."
m = p.search(s) # Run a regex search anywhere inside a string
if m: # If there is a match
print(m.group(1)) # Print Group 1 value
If you want to make sure test is matched as a whole word, add \b before it (do not remove the r prefix from the string literal, or '\b' will match a BACKSPACE char!) - r'\btest\s*:\s*(.*)\.'.

I don't see why you want to use regex if you're just getting a subset from a string.
This works the same way:
if line.startswith('test:'):
print(line[5:line.find('.')])
example:
>>> line = "test: match this."
>>> print(line[5:line.find('.')])
match this
Regex is slow, it is awkward to design, and difficult to debug. There are definitely occassions to use it, but if you just want to extract the text between test: and ., then I don't think is one of those occasions.
See: https://softwareengineering.stackexchange.com/questions/113237/when-you-should-not-use-regular-expressions
For more flexibility (for example if you are looping through a list of strings you want to find at the beginning of a string and then index out) replace 5 (the length of 'test:') in the index with len(str_you_looked_for).

Match everything except a pattern and replace matched with string

I want to use python in order to manipulate a string I have.
Basically, I want to prepend"\x" before every hex byte except the bytes that already have "\x" prepended to them.
My original string looks like this:
mystr = r"30336237613131\x90\x01\x0A\x90\x02\x146F6D6D616E64\x90\x01\x06\x90\x02\x0F52656C6174\x90\x01\x02\x90\x02\x50656D31\x90\x00"
And I want to create the following string from it:
mystr = r"\x30\x33\x62\x37\x61\x31\x31\x90\x01\x0A\x90\x02\x14\x6F\x6D\x6D\x61\x6E\x64\x90\x01\x06\x90\x02\x0F\x52\x65\x6C\x61\x74\x90\x01\x02\x90\x02\x50\x65\x6D\x31\x90\x00"
I thought of using regular expressions to match everything except /\x../g and replace every match with "\x". Sadly, I struggled with it a lot without any success. Moreover, I'm not sure that using regex is the best approach to solve such case.

Regex: (?:\\x)?([0-9A-Z]{2}) Substitution: \\x$1
Details:
(?:) Non-capturing group
? Matches between zero and one time, match string \x if it exists.
() Capturing group
[] Match a single character present in the list 0-9 and A-Z
{n} Matches exactly n times
\\x String \x
$1 Group 1.
Python code:
import re
text = R'30336237613131\x90\x01\x0A\x90\x02\x146F6D6D616E64\x90\x01\x06\x90\x02\x0F52656C6174\x90\x01\x02\x90\x02\x50656D31\x90\x00'
text = re.sub(R'(?:\\x)?([0-9A-Z]{2})', R'\\x\1', text)
print(text)
Output:
\x30\x33\x62\x37\x61\x31\x31\x90\x01\x0A\x90\x02\x14\x6F\x6D\x6D\x61\x6E\x64\x90\x01\x06\x90\x02\x0F\x52\x65\x6C\x61\x74\x90\x01\x02\x90\x02\x50\x65\x6D\x31\x90\x00
Code demo

You don't need regex for this. You can use simple string manipulation. First remove all of the "\x" from your string. Then add add it back at every 2 characters.
replaced = mystr.replace(r"\x", "")
newstr = "".join([r"\x" + replaced[i*2:(i+1)*2] for i in range(len(replaced)/2)])
Output:
>>> print(newstr)
\x30\x33\x62\x37\x61\x31\x31\x90\x01\x0A\x90\x02\x14\x6F\x6D\x6D\x61\x6E\x64\x90\x01\x06\x90\x02\x0F\x52\x65\x6C\x61\x74\x90\x01\x02\x90\x02\x50\x65\x6D\x31\x90\x00

You can get a list with your values to manipulate as you wish, with an even simpler re pattern
mystr = r"30336237613131\x90\x01\x0A\x90\x02\x146F6D6D616E64\x90\x01\x06\x90\x02\x0F52656C6174\x90\x01\x02\x90\x02\x50656D31\x90\x00"
import re
pat = r'([a-fA-F0-9]{2})'
match = re.findall(pat, mystr)
if match:
print('\n\nNew string:')
print('\\x' + '\\x'.join(match))
#for elem in match: # match gives you a list of strings with the hex values
# print('\\x{}'.format(elem), end='')
print('\n\nOriginal string:')
print(mystr)

This can be done without replacing existing \x by using a combination of positive lookbehinds and negative lookaheads.
(?!(?<=\\x)|(?<=\\x[a-f\d]))([a-f\d]{2})
Usage
See code in use here
import re
regex = r"(?!(?<=\\x)|(?<=\\x[a-f\d]))([a-f\d]{2})"
test_str = r"30336237613131\x90\x01\x0A\x90\x02\x146F6D6D616E64\x90\x01\x06\x90\x02\x0F52656C6174\x90\x01\x02\x90\x02\x50656D31\x90\x00"
subst = r"\\x$1"
result = re.sub(regex, subst, test_str, 0, re.IGNORECASE)
if result:
print (result)
Explanation
(?!(?<=\\x)|(?<=\\x[a-f\d])) Negative lookahead ensuring either of the following doesn't match.
(?<=\\x) Positive lookbehind ensuring what precedes is \x.
(?<=\\x[a-f\d]) Positive lookbehind ensuring what precedes is \x followed by a hexidecimal digit.
([a-f\d]{2}) Capture any two hexidecimal digits into capture group 1.