Python | Convert list of strings to space separated string

Given a list of strings, write a Python program to convert the given list of strings into a space-separated string. 

Examples:

Input : ['geeks', 'for', 'geeks']
Output : geeks for geeks

Input : ['Python', 'Language']
Output : Python Language

Approach #1 : Python string translate() The string translate() method returns a string where each character is mapped to its corresponding character in the translation table. The limitation of this method is that it does not work for Python 3 and above versions. 

Python

# Python3 program to Convert a list of
# strings to space-separated string

def convert(lst):

    return str(lst).translate(None, '[],\'')

# Driver code
lst = ['geeks', 'for', 'geeks']
print(convert(lst))

Output:

geeks for geeks

Time complexity is O(n), where n is the length of the input string.
Auxiliary space: O(n) where n is the length of the input list “lst”. 

Approach #2 : join() function The join() method is a string method and returns a string in which the elements of sequence have been joined by str separator. In this approach space is the separator. 

Python3

# Python3 program to Convert list of
# strings to space separated string

def convert(lst):

    return ' '.join(lst)

# Driver code
lst = ['geeks', 'for', 'geeks']
print(convert(lst))

Output:

geeks for geeks

Time complexity: O(n) where n is the number of elements in the list.
Auxiliary space: O(n) as the space required is proportional to the number of elements in the list.

Approach #3: Using for loop

Step-by-step approach :

• Define a function named “convert” that takes a list as an argument.
• Initialize an empty string “x“.
• Loop through the items of the input list “lst“.
  • In each iteration, concatenate the current item and space to the string “x“.
• After the loop, remove any leading or trailing whitespace from the string “x” using the strip() method.
• Return the modified string “x“.
• Define a list “lst” with three string items.
• Call the “convert” function with the “lst” as an argument.
• Print the returned string.

Below is the implementation of the above approach:

Python3

# Python3 program to Convert list of
# strings to space separated string

def convert(lst):
    x=""
    for i in lst:
        x+=i+" "
    x.strip()
    return x


# Driver code
lst = ['geeks', 'for', 'geeks']
print(convert(lst))

Output

geeks for geeks 

Time complexity: O(n), where n is the length of the input list.
Auxiliary space: O(n), where n is the length of the input list.

Approach #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 which concatenates the current element with a space and the next element.

Python3

from functools import reduce

def convert(lst):
    # using reduce function to cumulatively apply lambda function to each element
    # in the list and concatenate them with space
    return reduce(lambda x,y: x + ' ' + y, lst)

#Driver code
lst = ['geeks', 'for', 'geeks']
print(convert(lst))
#This code is contributed by Edula Vinay Kumar Reddy

Output

geeks for geeks

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.

 Method 5: Use the map() function along with the join() method.

Here’s the step-by-step approach:

• Define a function called convert that takes a list as input.
• Use the map() function with the str.strip() method to remove whitespace from each string element in the list.
• Use the join() method to join the stripped elements with a space separator.
• Return the resulting string.

Python3

def convert(lst):
    stripped_list = map(str.strip, lst)
    return ' '.join(stripped_list)

# Driver code
lst = ['geeks', 'for', 'geeks']
print(convert(lst))

Output

geeks for geeks

Time complexity: O(n), where n is the length of the list.
Auxiliary space: O(n), as we are creating a new string to return. However, since strings in Python are immutable, the space complexity could be slightly higher due to the creation of temporary string objects during the execution.