Python | Append String to list

, Sometimes, while working with data, we can have a problem in which we need to add elements to a container. The list can contain any type of data type. Let’s discuss certain ways in which we can perform string append operations in the list of integers.

Method #1 : Using + operator + list conversion In this method, we first convert the string into a list and then perform the task of append using + operator. 

Python3

# Python3 code to demonstrate working of
# Appending String to list
# using + operator + list conversion

# initialize list
test_list = [1, 3, 4, 5]

# initialize string
test_str = 'gfg'

# printing original list
print("The original list : " + str(test_list))

# printing original string
print("The original string : " + str(test_str))

# Appending String to list
# using + operator + list conversion
test_list += [test_str]

# printing result
print("The list after appending is : " + str(test_list))

Output

The original list : [1, 3, 4, 5]
The original string : gfg
The list after appending is : [1, 3, 4, 5, 'gfg']

Time Complexity: O(1)

Auxiliary Space: O(1)

Method #2: Using append() This particular function can be used to perform the operation of appending a string element to the end of a list without changing the state of the string to a list of characters. 

Python3

# Python3 code to demonstrate working of
# Appending String to list
# using append()

# initialize list
test_list = [1, 3, 4, 5]

# initialize string
test_str = 'gfg'

# printing original list
print("The original list : " + str(test_list))

# printing original string
print("The original string : " + str(test_str))

# Appending String to list
# using append()
test_list.append(test_str)

# printing result
print("The list after appending is : " + str(test_list))

Output

The original list : [1, 3, 4, 5]
The original string : gfg
The list after appending is : [1, 3, 4, 5, 'gfg']

Time Complexity: O(1)

Auxiliary Space: O(1)

Method#3: Using insert() This function is used to insert and add the element at the last of the list by using the length of the list as the index number. 

Python3

# Python3 code to demonstrate working of
# Appending String to list
# using insert()

# initialize list
test_list = [1, 3, 4, 5]

# initialize string
test_str = 'gfg'

# printing original list
print("The original list : " + str(test_list))

# printing original string
print("The original string : " + str(test_str))

# Index for insert method
index = len(test_list)
# Appending String to list
# using insert()
test_list.insert(index, test_str)

# printing result
print("The list after appending is : " + str(test_list))

Output

The original list : [1, 3, 4, 5]
The original string : gfg
The list after appending is : [1, 3, 4, 5, 'gfg']

Time Complexity: O(1)

Auxiliary Space: O(1)

Method#4: Using extend(): This method can be used to solve this problem, extend function is used to merge the one list to the end of second list. We add a string to the end of the list by using extend function. 

Python3

# Python3 code to demonstrate working of
# Appending String to list
# using extend()

# initialize list
test_list = [1, 3, 4, 5]

# initialize string
test_str = 'gfg'

# printing original list
print("The original list : " + str(test_list))

# printing original string
print("The original string : " + str(test_str))


# Appending String to list
# using extend()
test_list.extend([test_str])

# printing result
print("The list after appending is : " + str(test_list))

Output

The original list : [1, 3, 4, 5]
The original string : gfg
The list after appending is : [1, 3, 4, 5, 'gfg']

Time Complexity: O(1)

Auxiliary Space: O(1)

Method #5 : Using itertools.chain()
In this method, we can use itertools.chain() function to concatenate the given list and string element.

Python3

# Python3 code to demonstrate working of
# Appending String to list
# using itertools.chain()
import itertools

# initialize list
test_list = [1, 3, 4, 5]

# initialize string
test_str = 'gfg'

# printing original list
print("The original list : " + str(test_list))

# printing original string
print("The original string : " + str(test_str))

# Appending String to list
# using itertools.chain()
test_list = list(itertools.chain(test_list, [test_str]))

# printing result
print("The list after appending is : " + str(test_list))
#this code is contributed by edula vinay kumar reddy

Output

The original list : [1, 3, 4, 5]
The original string : gfg
The list after appending is : [1, 3, 4, 5, 'gfg']

Time Complexity: O(1)
Space Complexity: O(N)

Method #6:Using the slicing operator

Python3

# Initialize the list
my_list = ["apple", "banana", "cherry"]

# Append a string to the list
my_list = my_list[:len(my_list)] + ["date"]

# Print the updated list
print(my_list)

#This code is contributed by Vinay Pinjala.

Output

['apple', 'banana', 'cherry', 'date']

Time Complexity: O(N)
Space Complexity: O(1)

Method #7: Using the map() and join() method

map(str, test_str), str() is a built-in Python function that converts any value to a string. In this case, it is used to convert each character of the test_str to a single string. The map() function applies each element of the iterable object passed to it. Since we want to append the test_str to the list, we need to join the individual strings created by map() into a single string. So, “”.join(map(str, test_str)) creates a single string by joining the individual strings 

Python3

# initialize list
test_list = [1, 3, 4, 5]

# initialize string
test_str = "gfg"

# printing original list
print("The original list : " + str(test_list))

# printing original string
print("The original string : " + str(test_str))

# append string to list using map() function
test_list += ["".join(map(str, test_str))]

# print the updated list
print("The list after appending is : " + str(test_list))

Output

The original list : [1, 3, 4, 5]
The original string : gfg
The list after appending is : [1, 3, 4, 5, 'gfg']

Time Complexity: O(N) as we are iterating to each element, where N is the size of the list
Space Complexity: O(N) as we use map function which takes O(N) space.

Method#8:Using reduce() method.

Algorithm:

1. Import the reduce function from the functools module.
2. Initialize a list test_list and a string test_str.
3. Define a lambda function concatenate that takes two arguments x and y.
4. Inside the lambda function, join the list y into a string and concatenate it to the list x.
5. Use the reduce function to apply the concatenate lambda function to test_list and test_str.
6. Store the result in the variable result_list.
7. Print the updated list.

Python3

from functools import reduce

# initialize list
test_list = [1, 3, 4, 5]

# initialize string
test_str = "gfg"

# Define a lambda function to concatenate the string to the list
concatenate = lambda x, y: x + ["".join(map(str, y))]

# Append the string to the list using reduce() function
result_list = reduce(concatenate, [test_list, test_str])

# print the updated list
print("The list after appending is : " + str(result_list))

Output

The list after appending is : [1, 3, 4, 5, 'gfg']

The time complexity of the reduce() function is O(n), where n is the number of elements in the list.
The lambda function has a time complexity of O(1) because it only performs a single concatenation operation.

The space complexity of the algorithm is O(n) because it creates a new list with the concatenated string.
Therefore, the overall time complexity of the algorithm is O(n), and the overall space complexity is O(n).