Python | Convert None to empty string

Sometimes, while working with Machine Learning, we can encounter None values and we wish to convert to the empty string for data consistency. This and many other utilities can require the solution to this problem. Let’s discuss certain ways in which this problem can be solved. 

Method #1 : Using lambda This task can be performed using the lambda function. In this we check for string for None or empty string using the or operator and replace the None values with empty string. 

Python3

# Python3 code to demonstrate working of
# Converting None to empty string
# Using lambda

# initializing list of strings
test_list = ["Geeks", None, "CS", None, None]

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

# using lambda
# Converting None to empty string
conv = lambda i : i or ''
res = [conv(i) for i in test_list]

# printing result
print("The list after conversion of None values : " + str(res))

Output : 

The original list is : ['Geeks', None, 'CS', None, None]
The list after conversion of None values : ['Geeks', '', 'CS', '', '']

Method #2 : Using str() Simply the str function can be used to perform this particular task because, None also evaluates to a “False” value and hence will not be selected and rather a string converted false which evaluates to empty string is returned. 

Python3

# Python3 code to demonstrate working of
# Converting None to empty string
# Using str()

# initializing list of strings
test_list = ["Geeks", None, "CS", None, None]

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

# using str()
# Converting None to empty string
res = [str(i or '') for i in test_list]

# printing result
print("The list after conversion of None values : " + str(res))

Output : 

The original list is : ['Geeks', None, 'CS', None, None]
The list after conversion of None values : ['Geeks', '', 'CS', '', '']

Method #3 : Using map()
We can also use the map function to convert None values to empty strings

Python3

# Python3 code to demonstrate working of
# Converting None to empty string
# Using map()

# initializing list of strings
test_list = ["Geeks", None, "CS", None, None]

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

# Using map()
# Converting None to empty string
res = list(map(lambda x: x if x is not None else "", test_list))

# printing result
print("The list after conversion of None values : " + str(res))
#This code is contributed by Edula Vinay Kumar Reddy

Output

The original list is : ['Geeks', None, 'CS', None, None]
The list after conversion of None values : ['Geeks', '', 'CS', '', '']

All above example code has O(n) time complexity, where n is the number of element in the list and O(n) space complexity.