Python | Ways to convert list of ASCII value to string

Given a list of ASCII values, write a Python program to convert those values to their character and make a string. Given below are a few methods to solve the problem. 

Method #1: Using Naive Method

Python3

# Python code to demonstrate
# conversion of list of ascii values
# to string

# Initialising list
ini_list = [71, 101, 101, 107, 115, 102,
        111, 114, 71, 101, 101, 107, 115]

# Printing initial list
print ("Initial list", ini_list)

# Using Naive Method
res = ""
for val in ini_list:
    res = res + chr(val)

# Printing resultant string
print ("Resultant string", str(res))

Output

Initial list [71, 101, 101, 107, 115, 102, 111, 114, 71, 101, 101, 107, 115]
Resultant string GeeksforGeeks

Time Complexity: O(n) where n is the number of elements in the list “ini_list”.  
Auxiliary Space: O(n), where n is the number of elements in the new res list 

Method #2: Using map()

Python3

# Python code to demonstrate
# conversion of list of ascii values
# to string

# Initialising list
ini_list = [71, 101, 101, 107, 115, 102,
            111, 114, 71, 101, 101, 107, 115]

# Printing initial list
print ("Initial list", ini_list)

# Using map and join
res = ''.join(map(chr, ini_list))

# Print the resultant string
print ("Resultant string", str(res))

Output

Initial list [71, 101, 101, 107, 115, 102, 111, 114, 71, 101, 101, 107, 115]
Resultant string GeeksforGeeks

Time Complexity: O(n) where n is the number of elements in the list “ini_list”.  
Auxiliary Space: O(n), where n is the number of elements in the new res list 

Method #3: Using join and list comprehension

Python3

# Python code to demonstrate
# conversion of a list of ascii values
# to string

# Initialising list
ini_list = [71, 101, 101, 107, 115, 102,
            111, 114, 71, 101, 101, 107, 115]

# Printing initial list
print ("Initial list", ini_list)

# Using list comprehension and join
res = ''.join(chr(val) for val in ini_list)

# Print the resultant string
print ("Resultant string", str(res))

Output

Initial list [71, 101, 101, 107, 115, 102, 111, 114, 71, 101, 101, 107, 115]
Resultant string GeeksforGeeks

Time Complexity: O(n) where n is the number of elements in the list “test_list”. Using join and list comprehension performs n number of operations.
Auxiliary Space: O(n), where n is the length of list

Method #4: Using reduce()

The reduce() function applies a function to an iterable, cumulatively reducing it to a single value. In this case, it applies a lambda function to each element in the list, where the lambda function takes in two arguments x and y. The lambda function concatenates the current element which is converted to character using chr() function with the next element, effectively joining all the elements in the list. The final output is a single string with all the characters in the list concatenated together.

Python3

from functools import reduce

# Initialising list
ini_list = [71, 101, 101, 107, 115, 102, 111, 114, 71, 101, 101, 107, 115]

# Printing initial list
print("Initial list", ini_list)

# Using reduce
res = reduce(lambda x, y: x + chr(y), ini_list, '')

# Printing resultant string
print("Resultant string", res)
#This code is contributed by Edula Vinay Kumar Reddy

Output

Initial list [71, 101, 101, 107, 115, 102, 111, 114, 71, 101, 101, 107, 115]
Resultant string GeeksforGeeks

Time Complexity: O(n), where n is the number of elements in the list
Auxiliary  Space: O(1) as we are not creating any new list and the concatenation is happening in place.