How to Get a Substring of a String in Python

How do I get a substring of a string in Python?

>>> x = "Hello World!"
>>> x[2:]
'llo World!'
>>> x[:2]
'He'
>>> x[:-2]
'Hello Worl'
>>> x[-2:]
'd!'
>>> x[2:-2]
'llo Worl'

Python calls this concept "slicing" and it works on more than just strings. Take a look here for a comprehensive introduction.

How to get a string after a specific substring?

The easiest way is probably just to split on your target word

my_string="hello python world , i'm a beginner"
print(my_string.split("world",1)[1])

split takes the word (or character) to split on and optionally a limit to the number of splits.

In this example, split on "world" and limit it to only one split.

How to get the substring between two markers in Python multiple times?

you can use regex

import re
s = '''alt="Thunder Force"/>ehkjehkljhiflealt="Godzilla vs. Kong"/>'''
x = re.findall(r'alt="(.*?)"/>', s)
print(x)

output

['Thunder Force', 'Godzilla vs. Kong']

Getting Substring in Python

You can still use find if you want, find first position of | and next one:

fullstr = "my|name|is|will"
begin = fullstr.find('|')+1
end = fullstr.find('|', begin)
print fullstr[begin:end]

Similar way using index:

fullstr = "my|name|is|will"
begin = fullstr.index('|')+1
end = fullstr.index('|', begin)
print fullstr[begin:end]

Another way is to find all occurrences of | in your string using re.finditer and slice it by indexes:

import re

all = [sub.start() for sub in re.finditer('\|', fullstr)]
print fullstr[all[0]+1:all[1]] 

You can also take a look into re.search:

import re

fullstr = "my|name|is|will"
print re.search(r'\|([a-z]+)\|', fullstr).group(1)

There is an interesting way using enumerate:

fullstr = "my|name|is|will"
all = [p for p, e in enumerate(fullstr) if e == '|']
print fullstr[all[0]+1:all[1]]

And the easiest way just using split or rsplit:

fullstr = "my|name|is|will"
fullstr.split('|')[1]
fullstr.rsplit('|')[1]

Does Python have a string 'contains' substring method?

Use the in operator:

if "blah" not in somestring: 
    continue

How to extract the substring between two markers?

Using regular expressions - documentation for further reference

import re

text = 'gfgfdAAA1234ZZZuijjk'

m = re.search('AAA(.+?)ZZZ', text)
if m:
    found = m.group(1)

# found: 1234

or:

import re

text = 'gfgfdAAA1234ZZZuijjk'

try:
    found = re.search('AAA(.+?)ZZZ', text).group(1)
except AttributeError:
    # AAA, ZZZ not found in the original string
    found = '' # apply your error handling

# found: 1234

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