Given a list, the task is to write a Python program to concatenate all elements in a list into a string i.e. we are given a list of strings and we expect a result as the entire list is concatenated into a single sentence and printed as the output.
Examples:
Input: ['hello', 'geek', 'have', 'a', 'geeky', 'day'] Output: hello geek have a geeky day
Using the Naive approach to concatenate items in a list to a single string
Here, we are taking a list of words, and by using the Python loop we are iterating over each element and concatenating words with the help of the “+” operator.
Python3
l = [ 'hello', 'geek', 'have',
'a', 'geeky', 'day']
ans = ' '
for
i in l:
ans = ans+ ' '+ i
print[ans]
Output:
hello geek have a geeky day
Using list comprehension to concatenate items in a list to a single string
Here, we are using list comprehension to make the items into a Python string i.e. words into sentence.
Python3
l = [ 'hello', 'geek', 'have',
'a', 'geeky', 'day']
res = " ".join[[str[item] for item in l]]
res
Output:
'hello geek have a geeky day'
Using join[] method to concatenate items in a list to a single string
The join[]is an inbuilt string function in Python used to join elements of the sequence separated by a string separator. This function joins elements of a sequence and makes it a string.
Python3
l = ['hello', 'geek', 'have',
'a', '1', 'day']
l = ' '.join[l]
print[l]
Output:
hello geek have a 1 day
Using map[] method to concatenate items in a list to a single string
The map[] function returns a map object[which is an iterator] of the results after applying the given function to each item of a given iterable. In map we passed the str as Datatype and list, this will iterate till the length of the list and join each element to form a string.
Python3
l = [ 'hello', 'geek', 'have',
'a', 'geeky', 'day']
res = " ".join[map[str, l]]
print[res]
Output:
hello geek have a geeky day
Using reduce[] method to concatenate items in a list to a single string
The reduce[fun, seq] function is used to apply a particular function passed in its argument to all of the list elements mentioned in the sequence passed along. This function is defined in “functools” module.
Python3
from functools import reduce
l = ['hello', 'geek', 'have',
'a', 'geeky', 'day']
res = reduce[lambda x, y: x + ' ' + y, map[str, l]]
print[res]
Output:
hello geek have a geeky day
The time and space complexity for all the methods are the same:
Time Complexity: O[n]
Space Complexity: O[n]