Empty String to None Conversion - Python

Last Updated : 05 Feb, 2025

We are given a empty string we need to convert string to None. For example s = "" we are given a string we need to convert that to None so that out output becomes None.

Using Ternary

Ternary operator in Python allows us to perform conditional expressions in a single line. We can use it to convert an empty string to None by checking if the string is empty and assigning None if true or keeping original string otherwise.

Python

s = ""
# Use a ternary operator to convert the empty string to None
s = None if s == "" else s
print(s)

Output

None

Explanation:

Ternary operator checks if s is an empty string (s == ""). If true, it assigns None to s; otherwise, it keeps the original value of s.
Since s is an empty string the result is None.

Using or Operator

or operator in Python returns first truthy value it encounters or last value if none are truthy. We can use it to convert an empty string to None as an empty string is false and will result in None.

Python

s = ""
# Use the or operator to convert the empty string to None
s = s or None
print(s)

Output

None

Explanation:

or operator evaluates s and, since an empty string is false it assigns None to s.
If s had a truthy value it would have been returned instead of None.

Using if Statement

if statement can be used to explicitly check if the string is empty and if true assign None to the variable. Otherwise original string is retained. This makes logic clear and straightforward.

Python

s = ""

# Check if the string is empty, and if so, assign None to s
if s == "":
    s = None
print(s)

Output

None

Explanation:

if statement checks if the string s is empty (s == ""). If true None is assigned to s.
Since s is an empty string condition is met and output is None.

Using map()

map() function applies a given function to each item in an iterable producing a new iterable with the results. It can be used to convert empty strings to None by defining a function that checks for empty strings and replaces them.

Python

a = ["", "hello", "", "world"]

# Use map() with a lambda function to convert empty strings to None
a = list(map(lambda x: None if x == "" else x, a))
print(a)

Output

[None, 'hello', None, 'world']

Explanation:

map() applies lambda function to each element in the list a lambda function returns None for empty strings and original element for non-empty strings.
list() converts result from map() back into a list and output shows that empty strings have been replaced by None