Convert String to Boolean in Python

General Discussions
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1

How do I convert a string to boolean in Python? For example, this attempt returns True:

>>> bool("False")
True

What is the correct way to convert a python string to boolean value, especially when the string represents "False"?

2

I’ve worked with similar scenarios often, and the simplest way I’ve found is to use str.lower() combined with comparison. This ensures a case-insensitive conversion of a python string to boolean. Here’s how:

def str_to_bool(s):
    return s.strip().lower() == 'true'

print(str_to_bool("False"))  # Outputs: False  
print(str_to_bool("True"))   # Outputs: True

This method works effectively because it explicitly checks for "true" as a string, returning True only for that exact match and False for everything else.

3

I’ve seen this come up often, and another method that’s flexible is using a dictionary for mapping strings to boolean values. It’s great if you need to handle additional cases in your python string to boolean conversion.

def str_to_bool(s):
    return {
        "true": True,
        "false": False
    }.get(s.strip().lower(), False)

print(str_to_bool("False"))  # Outputs: False  
print(str_to_bool("True"))   # Outputs: True

This approach is particularly handy because you can easily expand it to handle strings like "yes" or "no" if needed.

4

Building on the previous solutions, here’s a more robust option if you want something from Python’s standard library. The strtobool function from distutils.util handles a variety of truthy and falsy strings. It’s super convenient when converting a python string to boolean.

from distutils.util import strtobool

def str_to_bool(s):
    return bool(strtobool(s))

print(str_to_bool("False"))  # Outputs: False  
print(str_to_bool("True"))   # Outputs: True

This method recognizes common inputs like "y", "yes", "1" as True and "n", "no", "0" as False. If your use case involves varied inputs, this could save you a lot of hassle.