[Tut] Python | Split String by Number

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Python | Split String by Number

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Summary: To split a string by a number, use the regex

Code:

split

method using the “

Code:

\d

” pattern.

[b]Minimal Example[/b]

Code:

my_string = "#@1abc3$!*5xyz" # Method 1 import re res = re.split('\d+', my_string) print(res) # Method 2 import re res = re.findall('\D+', my_string) print(res) # Method 3 from itertools import groupby li = [''.join(g) for _, g in groupby(my_string, str.isdigit)] res = [x for x in li if x.isdigit() == False] print(res) # Method 4 res = [] for i in my_string: if i.isdigit() == True: my_string = my_string.replace(i, ",") print(my_string.split(",")) # Outputs: # ['#@', 'abc', '$!*', 'xyz']

[b]Problem Formulation[/b]

Problem: Given a string containing different characters. How will you split the string whenever a number appears?

Method 1: re.split()

The 

Code:

re.split(pattern, string)

 method matches all occurrences of the 

Code:

pattern

 in the 

Code:

string

 and divides the string along the matches resulting in a list of strings between the matches. For example, 

Code:

re.split('a', 'bbabbbab')

 results in the list of strings 

Code:

['bb', 'bbb', 'b']

.

Code:

Code:

import re my_string = "#@1abc3$!*5xyz" res = re.split('\d+', my_string) print(res) # ['#@', 'abc', '$!*', 'xyz']

Explanation: The 

Code:

\d

 special character matches any digit between 0 and 9. By using the maximal number of digits as a delimiter, you split along the digit-word boundary. 

Method 2: re.findall()

The 

Code:

re.findall(pattern, string)

 method scans 

Code:

string

 from left to right, searching for all non-overlapping matches of the 

Code:

pattern

. It returns a list of strings in the matching order when scanning the string from left to right.

Code:

Code:

import re my_string = "#@1abc3$!*5xyz" res = re.findall('\D+', my_string) print(res) # ['#@', 'abc', '$!*', 'xyz']

Explanation: The 

Code:

\

D special character matches all characters except any digit between 0 and 9. Thus, you are essentially finding all character groups that appear before the occurrence of a digit.

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Method 3: itertools.groupby()

Code:

Code:

from itertools import groupby my_string = "#@1abc3$!*5xyz" li = [''.join(g) for _, g in groupby(my_string, str.isdigit)] res = [x for x in li if x.isdigit() == False] print(res) # ['#@', 'abc', '$!*', 'xyz']

Explanation:

• The 
  Code:

  itertools.groupby(iterable, key=None)
   function creates an iterator that returns tuples 
  Code:

  (key, group-iterator)
   grouped by each value of 
  Code:

  key
  . We use the 
  Code:

  str.isdigit()
   function as key function.
  
  
• The 
  Code:

  str.isdigit()
   function returns 
  Code:

  True
   if the string consists only of numeric characters. Thus, you will have a list created by using numbers as separators. Note that this list will also contain the numbers as items within it.
  
  
• In order to eliminate the numbers, use another list comprehension that checks if an element in the list returned previously is a digit or not with the help of the
  Code:

  isdigit
  method. If it is a digit, the item will be discarded. Otherwise it will be stored in the list.
  

Method 4: Replace Using a for Loop

Approach: Use a for loop to iterate through the characters of the given string. Check if a character is a digit or not. As soon as a digit is found, replace that character/digit with a delimiter string ( we have used a comma here) with the help of the replace() method. This basically means that you are placing a particular character in the string whenever a number appears. Once all the digits are replaced by the separator string, split the string by passing the separator string as a delimiter to the split method.

Code:

Code:

my_string = "#@1abc3$!*5xyz" res = [] for i in my_string: if i.isdigit(): my_string = my_string.replace(i, ",") print(my_string.split(",")) # ['#@', 'abc', '$!*', 'xyz']

[b]Conclusion[/b]

Phew! We have successfully solved the given problem and managed to do so using four different ways. I hope you found this article helpful and it answered your queries. Please subscribe and stay tuned for more solutions and tutorials.

Happy coding!

Related Read:How to Split a String Between Numbers and Letters?