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How I can use regex to remove repeated characters from string

I have a string as follows where I tried to remove similar consecutive characters.
import re
input = "abccbcbbb";
for i in input :
input = re.sub("(.)\\1+", "",input);
print(input)
Now I need to let the user specify the value of k.
I am using the following python code to do it, but I got the error message TypeError: can only concatenate str (not "int") to str
import re
input = "abccbcbbb";
k=3
for i in input :
input= re.sub("(.)\\1+{"+(k-1)+"}", "",input)
print(input)

The for i in input : does not do what you need. i is each character in the input string, and your re.sub is supposed to take the whole input as a char sequence.
If you plan to match a specific amount of chars you should get rid of the + quantifier after \1. The limiting {min,} / {min,max} quantifier should be placed right after the pattern it modifies.
Also, it is more convenient to use raw string literals when defining regexps.
You can use
import re
input_text = "abccbcbbb";
k=3
input_text = re.sub(fr"(.)\1{{{k-1}}}", "", input_text)
print(input_text)
# => abccbc
See this Python demo.
The fr"(.)\1{{{k-1}}}" raw f-string literal will translate into (.)\1{2} pattern. In f-strings, you need to double curly braces to denote a literal curly brace and you needn't escape \1 again since it is a raw string literal.

If I were you, I would prefer to do it like suggested before. But since I've already spend time on answering this question here is my handmade solution.
The pattern described below creates a named group named "letter". This group updates iterative, so firstly it is a, then b, etc. Then it looks ahead for all the repetitions of the group "letter" (which updates for each letter).
So it finds all groups of repeated letters and replaces them with empty string.
import re
input = 'abccbcbbb'
result = 'abcbcb'
pattern = r'(?P<letter>[a-z])(?=(?P=letter)+)'
substituted = re.sub(pattern, '', input)
assert substituted == result

Just to make sure I have the question correct you mean to turn "abccbcbbb" into "abcbcb" only removing sequential duplicate characters. Is there a reason you need to use regex? you could likely do a simple list comprehension. I mean this is a really cut and dirty way to do it but you could just put
input = "abccbcbbb"
input = list(input)
previous = input.pop(0)
result = [previous]
for letter in input:
if letter != previous : result += letter
previous = letter
result = "".join(result)
and with a method like this, you could make it easier to read and faster with a bit of modification id assume.

Remove Characters From A String Until A Specific Format is Reached

So I have the following strings and I have been trying to figure out how to manipulate them in such a way that I get a specific format.
string1-itd_jan2021-internal
string2itd_mar2021-space
string3itd_feb2021-internal
string4-itd_mar2021-moon
string5itd_jun2021-internal
string6-itd_feb2021-apollo
I want to be able to get rid of any of the last string so I am just left with the month and year, like below:
string1-itd_jan2021
string2itd_mar2021
string3itd_feb2021
string4-itd_mar2021
string5itd_jun2021
string6-itd_feb2021
I thought about using string.split on the - but then realized that for some strings this wouldn't work. I also thought about getting rid of a set amount of characters by putting it into a list and slicing but the end is varying characters length?
Is there anything I can do it with regex or any other python module?

Use str.rsplit with the appropriate maxsplit parameter:
s = s.rsplit("-", 1)[0]
You could also use str.split (even though this is clearly the worse choice):
s = "-".join(s.split("-")[:-1])
Or using regular expressions:
s = re.sub(r'-[^-]*$', '', s)
# "-[^-]*" a "-" followed by any number of non-"-"

With a regex:
import re
re.sub(r'([0-9]{4}).*$', r'\1', s)

Use re.sub like so:
import re
lines = '''string1-itd_jan2021-internal
string2itd_mar2021-space
string3itd_feb2021-internal
string4-itd_mar2021-moon
string5itd_jun2021-internal
string6-itd_feb2021-apollo'''
for old in lines.split('\n'):
new = re.sub(r'[-][^-]+$', '', old)
print('\t'.join([old, new]))
Prints:
string1-itd_jan2021-internal string1-itd_jan2021
string2itd_mar2021-space string2itd_mar2021
string3itd_feb2021-internal string3itd_feb2021
string4-itd_mar2021-moon string4-itd_mar2021
string5itd_jun2021-internal string5itd_jun2021
string6-itd_feb2021-apollo string6-itd_feb2021
Explanation:
r'[-][^-]+$' : Literal dash (-), followed by any character other than a dash ([^-]) repeated 1 or more times, followed by the end of the string ($).

How to copy changing substring in string?

How can I copy data from changing string?
I tried to slice, but length of slice is changing.
For example in one case I should copy number 128 from string '"edge_liked_by":{"count":128}', in another I should copy 15332 from "edge_liked_by":{"count":15332}

You could use a regular expression:
import re
string = '"edge_liked_by":{"count":15332}'
number = re.search(r'{"count":(\d*)}', string).group(1)

Really depends on the situation, however I find regular expressions to be useful.
To grab the numbers from the string without caring about their location, you would do as follows:
import re
def get_string(string):
return re.search(r'\d+', string).group(0)
>>> get_string('"edge_liked_by":{"count":128}')
'128'
To only get numbers from the *end of the string, you can use an anchor to ensure the result is pulled from the far end. The following example will grab any sequence of unbroken numbers that is both preceeded by a colon and ends within 5 characters of the end of the string:
import re
def get_string(string):
rval = None
string_match = re.search(r':(\d+).{0,5}$', string)
if string_match:
rval = string_match.group(1)
return rval
>>> get_string('"edge_liked_by":{"count":128}')
'128'
>>> get_string('"edge_liked_by":{"1321":1}')
'1'
In the above example, adding the colon will ensure that we only pick values and don't match keys such as the "1321" that I added in as a test.
If you just want anything after the last colon, but excluding the bracket, try combining split with slicing:
>>> '"edge_liked_by":{"count":128}'.split(':')[-1][0:-1]
'128'
Finally, considering this looks like a JSON object, you can add curly brackets to the string and treat it as such. Then it becomes a nested dict you can query:
>>> import json
>>> string = '"edge_liked_by":{"count":128}'
>>> string = '{' + string + '}'
>>> string = json.loads(string)
>>> string.get('edge_liked_by').get('count')
128
The first two will return a string and the final one returns a number due to being treated as a JSON object.

It looks like the type of string you are working with is read from JSON, maybe you are getting it as the output of some API you are working with?
If it is JSON, you've probably gone one step too far in atomizing it to a string like this. I'd work with the original output, if possible, if I were you.
If not, to make it more JSON like, I'd convert it to JSON by wrapping it in {}, and then working with the json.loads module.
import json
string = '"edge_liked_by":{"count":15332}'
string = "{"+string+"}"
json_obj = json.loads(string)
count = json_obj['edge_liked_by']['count']
count will have the desired output. I prefer this option to using regular expressions because you can rely on the structure of the data and reuse the code in case you wish to parse out other attributes, in a very intuitive way. With regular expressions, the code you use will change if the data are decimal, or negative, or contain non-numeric characters.

Does this help ?
a='"edge_liked_by":{"count":128}'
import re
b=re.findall(r'\d+', a)[0]
b
Out[16]: '128'

Best way to convert string to integer in Python

I have a spreadsheet with text values like A067,A002,A104. What is most efficient way to do this? Right now I am doing the following:
str = 'A067'
str = str.replace('A','')
n = int(str)
print n

Depending on your data, the following might be suitable:
import string
print int('A067'.strip(string.ascii_letters))
Python's strip() command takes a list of characters to be removed from the start and end of a string. By passing string.ascii_letters, it removes any preceding and trailing letters from the string.

If the only non-number part of the input will be the first letter, the fastest way will probably be to slice the string:
s = 'A067'
n = int(s[1:])
print n
If you believe that you will find more than one number per string though, the above regex answers will most likely be easier to work with.

You could use regular expressions to find numbers.
import re
s = 'A067'
s = re.findall(r'\d+', s) # This will find all numbers in the string
n = int(s[0]) # This will get the first number. Note: If no numbers will throw exception. A simple check can avoid this
print n
Here's some example output of findall with different strings
>>> a = re.findall(r'\d+', 'A067')
>>> a
['067']
>>> a = re.findall(r'\d+', 'A067 B67')
>>> a
['067', '67']

You can use the replace method of regex from re module.
import re
regex = re.compile("(?P<numbers>.*?\d+")
matcher = regex.search(line)
if matcher:
numbers = int(matcher.groupdict()["numbers"] #this will give you the numbers from the captured group

import string
str = 'A067'
print (int(str.strip(string.ascii_letters)))

Extracting text in the middle of a string - python

i was wondering if anyone has a simpler solution to extract a few letters in the middle of a string. i want to retrive the 3 letters (in this case, GMB) and all the entries follow the same patter. i'struggling o get a simpler way of doing this.
here is an example of what i've been using.
entry = "entries-alphabetical.jsp?raceid13=GMB$20140313A"
symbol = entry.strip('entries-alphabetical.jsp?raceid13=')
symbol = symbol[0:3]
print symbol
thanks

First of all the argument passed to str.strip is not prefix or suffix, it is just a combination of characters that you want to be stripped off from the string.
Since the string looks like an url, you can use urlparse.parse_qsl:
>>> import urlparse
>>> urlparse.parse_qsl(entry)
[('entries-alphabetical.jsp?raceid13', 'GMB$20140313A')]
>>> urlparse.parse_qsl(entry)[0][1][:3]
'GMB'

This is what regular expressions are for. http://docs.python.org/2/library/re.html
import re
val = re.search(r'(GMB.*)', entry)
print val.group(1)