How to extract the substring between two markers?

>>> s = 'gfgfdAAA1234ZZZuijjk'
>>> start = s.find('AAA') + 3
>>> end = s.find('ZZZ', start)
>>> s[start:end]
'1234'

Then you can use regexps with the re module as well, if you want, but that’s not necessary in your case.

import re
print re.search('AAA(.*?)ZZZ', 'gfgfdAAA1234ZZZuijjk').group(1)

You can use re module for that:

>>> import re
>>> re.compile(".*AAA(.*)ZZZ.*").match("gfgfdAAA1234ZZZuijjk").groups()
('1234,)

regular expression

import re

re.search(r"(?<=AAA).*?(?=ZZZ)", your_text).group(0)

The above as-is will fail with an AttributeError if there are no “AAA” and “ZZZ” in your_text

string methods

your_text.partition("AAA")[2].partition("ZZZ")[0]

The above will return an empty string if either “AAA” or “ZZZ” don’t exist in your_text.

PS Python Challenge?

Just in case somebody will have to do the same thing that I did. I had to extract everything inside parenthesis in a line. For example, if I have a line like ‘US president (Barack Obama) met with …’ and I want to get only ‘Barack Obama’ this is solution:

regex = '.*((.*?)).*'
matches = re.search(regex, line)
line = matches.group(1) + 'n'

I.e. you need to block parenthesis with slash sign. Though it is a problem about more regular expressions that Python.

Also, in some cases you may see ‘r’ symbols before regex definition. If there is no r prefix, you need to use escape characters like in C. Here is more discussion on that.

>>> s = '/tmp/10508.constantstring'
>>> s.split('/tmp/')[1].split('constantstring')[0].strip('.')

With sed it is possible to do something like this with a string:

echo "$STRING" | sed -e "s|.*AAA(.*)ZZZ.*|1|"

And this will give me 1234 as a result.

You could do the same with re.sub function using the same regex.

>>> re.sub(r'.*AAA(.*)ZZZ.*', r'1', 'gfgfdAAA1234ZZZuijjk')
'1234'

In basic sed, capturing group are represented by (..), but in python it was represented by (..).

You can find first substring with this function in your code (by character index). Also, you can find what is after a substring.

def FindSubString(strText, strSubString, Offset=None):
    try:
        Start = strText.find(strSubString)
        if Start == -1:
            return -1 # Not Found
        else:
            if Offset == None:
                Result = strText[Start+len(strSubString):]
            elif Offset == 0:
                return Start
            else:
                AfterSubString = Start+len(strSubString)
                Result = strText[AfterSubString:AfterSubString + int(Offset)]
            return Result
    except:
        return -1

# Example:

Text = "Thanks for contributing an answer to Stack Overflow!"
subText = "to"

print("Start of first substring in a text:")
start = FindSubString(Text, subText, 0)
print(start); print("")

print("Exact substring in a text:")
print(Text[start:start+len(subText)]); print("")

print("What is after substring "%s"?" %(subText))
print(FindSubString(Text, subText))

# Your answer:

Text = "gfgfdAAA1234ZZZuijjk"
subText1 = "AAA"
subText2 = "ZZZ"

AfterText1 = FindSubString(Text, subText1, 0) + len(subText1)
BeforText2 = FindSubString(Text, subText2, 0) 

print("nYour answer:n%s" %(Text[AfterText1:BeforText2]))

One liners that return other string if there was no match.
Edit: improved version uses next function, replace "not-found" with something else if needed:

import re
res = next( (m.group(1) for m in [re.search("AAA(.*?)ZZZ", "gfgfdAAA1234ZZZuijjk" ),] if m), "not-found" )

My other method to do this, less optimal, uses regex 2nd time, still didn’t found a shorter way:

import re
res = ( ( re.search("AAA(.*?)ZZZ", "gfgfdAAA1234ZZZuijjk") or re.search("()","") ).group(1) )

you can do using just one line of code

>>> import re

>>> re.findall(r'd{1,5}','gfgfdAAA1234ZZZuijjk')

>>> ['1234']

result will receive list…

In python, extracting substring form string can be done using findall method in regular expression (re) module.

>>> import re
>>> s = 'gfgfdAAA1234ZZZuijjk'
>>> ss = re.findall('AAA(.+)ZZZ', s)
>>> print ss
['1234']

Surprised that nobody has mentioned this which is my quick version for one-off scripts:

>>> x = 'gfgfdAAA1234ZZZuijjk'
>>> x.split('AAA')[1].split('ZZZ')[0]
'1234'

Here’s a solution without regex that also accounts for scenarios where the first substring contains the second substring. This function will only find a substring if the second marker is after the first marker.

def find_substring(string, start, end):
    len_until_end_of_first_match = string.find(start) + len(start)
    after_start = string[len_until_end_of_first_match:]
    return string[string.find(start) + len(start):len_until_end_of_first_match + after_start.find(end)]

text = 'I want to find a string between two substrings'
left = 'find a '
right = 'between two'

print(text[text.index(left)+len(left):text.index(right)])

Gives

string

Another way of doing it is using lists (supposing the substring you are looking for is made of numbers, only) :

string = 'gfgfdAAA1234ZZZuijjk'
numbersList = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
output = []

for char in string:
    if char in numbersList: output.append(char)

print(f"output: {''.join(output)}")
### output: 1234

Using PyParsing

import pyparsing as pp

word = pp.Word(pp.alphanums)

s = 'gfgfdAAA1234ZZZuijjk'
rule = pp.nestedExpr('AAA', 'ZZZ')
for match in rule.searchString(s):
    print(match)

which yields:

[['1234']]

Typescript. Gets string in between two other strings.

Searches shortest string between prefixes and postfixes

prefixes – string / array of strings / null (means search from the start).

postfixes – string / array of strings / null (means search until the end).

public getStringInBetween(str: string, prefixes: string | string[] | null,
                          postfixes: string | string[] | null): string {

    if (typeof prefixes === 'string') {
        prefixes = [prefixes];
    }

    if (typeof postfixes === 'string') {
        postfixes = [postfixes];
    }

    if (!str || str.length < 1) {
        throw new Error(str + ' should contain ' + prefixes);
    }

    let start = prefixes === null ? { pos: 0, sub: '' } : this.indexOf(str, prefixes);
    const end = postfixes === null ? { pos: str.length, sub: '' } : this.indexOf(str, postfixes, start.pos + start.sub.length);

    let value = str.substring(start.pos + start.sub.length, end.pos);
    if (!value || value.length < 1) {
        throw new Error(str + ' should contain string in between ' + prefixes + ' and ' + postfixes);
    }

    while (true) {
        try {
            start = this.indexOf(value, prefixes);
        } catch (e) {
            break;
        }
        value = value.substring(start.pos + start.sub.length);
        if (!value || value.length < 1) {
            throw new Error(str + ' should contain string in between ' + prefixes + ' and ' + postfixes);
        }
    }

    return value;
}

One liner with Python 3.8 if text is guaranteed to contain the substring:

text[text.find(start:='AAA')+len(start):text.find('ZZZ')]

also, you can find all combinations in the bellow function

s = 'Part 1. Part 2. Part 3 then more text'
def find_all_places(text,word):
    word_places = []
    i=0
    while True:
        word_place = text.find(word,i)
        i+=len(word)+word_place
        if i>=len(text):
            break
        if word_place<0:
            break
        word_places.append(word_place)
    return word_places
def find_all_combination(text,start,end):
    start_places = find_all_places(text,start)
    end_places = find_all_places(text,end)
    combination_list = []
    for start_place in start_places:
        for end_place in end_places:
            print(start_place)
            print(end_place)
            if start_place>=end_place:
                continue
            combination_list.append(text[start_place:end_place])
    return combination_list
find_all_combination(s,"Part","Part")

result:

['Part 1. ', 'Part 1. Part 2. ', 'Part 2. ']

In case you want to look for multiple occurences.

content ="Prefix_helloworld_Suffix_stuff_Prefix_42_Suffix_andsoon"
strings = []
for c in content.split('Prefix_'):
    spos = c.find('_Suffix')
    if spos!=-1:
        strings.append( c[:spos])
print( strings )

Or more quickly :

strings = [ c[:c.find('_Suffix')] for c in content.split('Prefix_') if c.find('_Suffix')!=-1 ]

a simple approach could be the following:

string_to_search_in = 'could be anything'
start = string_to_search_in.find(str("sub string u want to identify"))
length = len("sub string u want to identify")
First_part_removed = string_to_search_in[start:]
end_coord = length
Extracted_substring=First_part_removed[:end_coord]