Python | Ways to split strings using newline delimiter

Given a string, write a Python program to split strings on the basis of newline delimiter. Given below are a few methods to solve the given task. 

Method #1: Using splitlines()

Step-by-step approach :

• Use the splitlines() method to split the ini_str string into a list of substrings. The splitlines() method is a built-in Python method that splits a string into substrings based on newline characters (\n) and returns the substrings as a list.
• Assigns the resulting list of substrings to a variable called res_list.
• Finally, the prints the resulting list using the print() function and the message “Resultant prefix“. The str() function is used to convert the list to a string before printing it.

Below is the implementation of the above approach:

Python3

# Python code to demonstrate
# to split strings
# on newline delimiter

# Initialising string
ini_str = 'Geeks\nFor\nGeeks\n'

# Printing Initial string
print ("Initial String", ini_str)

# Splitting on newline delimiter
res_list = ini_str.splitlines()

# Printing result
print("Resultant prefix", str(res_list))

Output:

Initial String Geeks
For
Geeks

Resultant prefix ['Geeks', 'For', 'Geeks']

Time complexity: O(n) – where n is the length of the input string.
Auxiliary Space: O(n) – the split string is stored in a list, which requires additional space in memory.

Method #2: Using split() method

Python3

# Python code to demonstrate
# to split strings
# on newline delimiter

# Initialising string
ini_str = 'Geeks\nFor\nGeeks\n'

# Printing Initial string
print ("Initial String", ini_str)

# Splitting on newline delimiter
res_list = (ini_str.rstrip().split('\n'))

# Printing result
print("Resultant prefix", str(res_list))

Output:

Initial String Geeks
For
Geeks

Resultant prefix ['Geeks', 'For', 'Geeks']

Time Complexity: O(n), where n is the length of the input string.
Auxiliary Space: O(1)

Method 3: Use the re module 

This will produce the same output as the splitlines() method. The re.split() function takes a regular expression as the delimiter, which in this case is simply \n.

Python3

import re

# Initialising string
ini_str = 'Geeks\nFor\nGeeks\n'

# Printing Initial string
print("Initial String", ini_str)

# Splitting on newline delimiter using re.split()
res_list = re.split(r'\n', ini_str)

# Printing result
print("Resultant prefix", str(res_list))

Output

Initial String Geeks
For
Geeks

Resultant prefix ['Geeks', 'For', 'Geeks', '']

Time complexity: O(n), where n is the length of the input string.
Auxiliary space: O(n), as the result list res_list will have the same length as the input string ini_str.

Method 4: Using the re.findall() method with a regular expression

The program uses the re module to split a string on the newline delimiter using the re.findall() method with the regular expression pattern [^\n]+. The initial string and the resultant list are printed using the print() function

Step-by-step approach:

• Import the re module.
• Initialize a string ini_str with the value “Geeks\nFor\nGeeks\n”.
• Print the initial string using the print() function with the message “Initial String:” and the value of ini_str.
• Use the re.findall() method with the regular expression pattern [^\n]+ and the ini_str string as input to split the string on the newline delimiter and obtain a list of non-overlapping substrings.
• Assign the resulting list to a variable res_list.
• Print the resultant list using the print() function with the message “Resultant list:” and the value of res_list.

Below is the implementation of the above approach:

Python3

# Importing the re module
import re

# Initialising string
ini_str = 'Geeks\nFor\nGeeks\n'

# Printing Initial string
print("Initial String:", ini_str)

# Using re.findall() method with regular expression pattern
res_list = re.findall(r'[^\n]+', ini_str)

# Printing result
print("Resultant list:", res_list)

Output

Initial String: Geeks
For
Geeks

Resultant list: ['Geeks', 'For', 'Geeks']

Time complexity: O(n) where n is the length of the input string
Auxiliary space: O(m) where m is the number of substrings obtained after splitting the input string on the newline delimiter.

Method #5: Using the StringIO module and the csv.reader() function

Step-by-step approach:

• Import the StringIO module and csv.reader() function.
• Create an instance of the StringIO object with the initial string as its argument.
• Pass the instance of StringIO object to csv.reader() function, along with the delimiter as the newline character ‘\n’.
• Convert the resulting csv.reader object to a list using the list() function.
• Print the list.

Below is the implementation of the above approach:

Python3

# Python code to demonstrate
# to split strings
# on newline delimiter

# import required modules
from io import StringIO
import csv

# Initialising string
ini_str = 'Geeks\nFor\nGeeks\n'

# Printing Initial string
print("Initial String", ini_str)

# Splitting using StringIO and csv.reader
res_list = list(csv.reader(StringIO(ini_str), delimiter='\n'))

# Printing result
print("Resultant prefix", str(res_list))

Output

Initial String Geeks
For
Geeks

Resultant prefix [['Geeks'], ['For'], ['Geeks']]

Time Complexity: O(n), where n is the length of the string ini_str.
Auxiliary Space: O(n), where n is the length of the string ini_str, as we are storing the string in the StringIO object.