Python | Get numeric prefix of given string

Sometimes, while working with strings, we might be in a situation in which we require to get the numeric prefix of a string. This kind of application can come in various domains such as web application development. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using re.findall()
The regex can be used to perform this particular task. In this, we use findall function which we use to get all the occurrences of numbers and then return the initial occurrence.

# Python3 code to demonstrate working of 
# Get numeric prefix of string  
# Using re.findall() 
import re 
  
# initializing string  
test_str = "1234Geeks"
  
# printing original string  
print("The original string is : " + test_str) 
  
# Using re.findall() 
# Get numeric prefix of string  
res = re.findall('\d+', test_str) 
  
# printing result  
print("The prefix number at string : " + str(res[0])) 

Output :

The original string is : 1234Geeks
The prefix number at string : 1234

Method #2 : Using itertools.takewhile()
The inbuilt function of takewhile can be used to perform this particular task of extracting all the numbers till a character occurs.

# Python3 code to demonstrate working of 
# Get numeric prefix of string  
# Using itertools.takewhile() 
from itertools import takewhile 
  
# initializing string  
test_str = "1234Geeks"
  
# printing original string  
print("The original string is : " + test_str) 
  
# Using itertools.takewhile() 
# Get numeric prefix of string  
res = ''.join(takewhile(str.isdigit, test_str)) 
  
# printing result  
print("The prefix number at string : " + str(res)) 

Output :

The original string is : 1234Geeks
The prefix number at string : 1234

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