How to Get a Negation of a Boolean in Python?

In this article, we will learn how to get a negation of a Boolean in Python.

In Python, the Boolean datatype is the built-in data type. It denotes the True or False values. For example, 5<20 is True and 10>20 is False. In this article, we will print the negation of a Boolean variable.

The following are the various methods to accomplish this task −

• Using the “~” operator

• Using “not” Operator

• Using Operator Module

• Using Minus the value from ‘1’

• Using bitwise_not(), logical_not() of Numpy Module

Method 1: Using the “~” operator

The negation of the operand can be returned using the bitwise NOT(“~”) operator.

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task. −

• Create a variable to store the input boolean value.

• Print the input boolean value.

• Use the ~ operator to print the negation of the input boolean value and print the resultant value.

• The bool() function will convert to a Boolean value if it is not already a boolean value before.

Example

The following program returns the negation of the input boolean value using the bitwise NOT(“~”) operator −

# input boolean value
inputBool = False

# printing the input boolean value
print("Input boolean value:", inputBool)

# Printing the negation of the input boolean value using the ~ operator
print("Negation of the input boolean value:", bool(~inputBool))

Output

On executing, the above program will generate the following output −

Input boolean value: False
Negation of the input boolean value: True

Method 2:Using “not” Operator

The not operator is a logical operator that returns the complement(negation) of the operand's Boolean value.

Use the not operator to print the negation of the input boolean value and print the resultant value.

Example

The following program returns the negation of the input boolean value using the “not” Operator −

# input boolean value
inputBool = False

# printing the input boolean value
print("Input boolean value:", bool(inputBool))

# Printing the negation of the input boolean 
# value using 'not' operator
print("Negation of the input boolean value:", not inputBool)

Output

On executing, the above program will generate the following output −

Input boolean value: False
Negation of the input boolean value: True

In the above example, we are using print(bool(inputBool)), as "inputBool" will be changed to a Boolean value if it is not already a boolean value before.

Example

The following program removes the last element from the set using the remove() function −

# input string
inputStr = "tutorialspoint"

# converting the input string into a boolean datatype
# using bool() function and printing a boolean value
print("Input boolean value:", bool(inputStr))

# Printing the negation of the boolean  
# value using 'not' operator
print("Negation of the input string:", not inputStr)

Output

On executing, the above program will generate the following output −

Input boolean value: True
Negation of the input string: False

Method 3: Using Operator Module

Use the following code to import the Operator module before running the program −

import operator

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task. −

• Use the import keyword to import the operator module.

• Use the bool() function to convert the input string into a boolean datatype and print a boolean value.

• Use the operator.not_() function to print the negation of the boolean value and print the resultant value.

Example

The following program returns the negation of the input boolean value using the operator.not_() function −

# importing operator module
import operator 

# input string
inputStr = "tutorialspoint"

# converting the input string into a boolean datatype
# using bool() function and printing a boolean value
print("Input boolean value:", bool(inputStr))

# Printing the negation of the boolean  
# value using the operator.not_() function
print("Negation of the input string:", operator.not_(inputStr))

Output

On executing, the above program will generate the following output −

Input boolean value: True
Negation of the input string: False

Method 4: Using Minus the value from ‘1’

Example

The following program returns the negation of the input boolean value using the function by subtracting the value from ‘1’ −

# input boolean value
inputBool = False
 
# printing the input boolean value
print("Input boolean value:", inputBool)

# getting the negation of the input boolean value
# by subtracting it from 1 and converting it to a boolean value
outputBool = bool(1-inputBool)

# printing the resultant boolean value
print("Output boolean value:", outputBool)

Output

Input boolean value: False
Output boolean value: True

Method 5: Using bitwise_not(), logical_not() of Numpy Module

bitwise_not() function − The bitwise_not() function of the NumPy module returns the negation of the given Boolean argument.

Example

The following program returns a list of negation values of the input boolean array values using the bitwise_not() function of the NumPy module −

# importing NumPy module with an alias name
import numpy as np 

# input NumPy array containing boolean elements
inputArray = np.array([False, True, True, False, False])

# converting input array to list and printing it 
print("Input List:", list(inputArray))

# getting the negation values of the input array
# using the bitwise_not() function of NumPy module
outputArray = np.bitwise_not(inputArray)

# converting output array to list and printing it 
print("Output List:", list(outputArray))

Output

Input List: [False, True, True, False, False]
Output List: [True, False, False, True, True]

Using numpy. logical_not() function

We can alternatively utilize the Numpy library's logical_not() method, which gives a Boolean value.

Example

The following program returns a list of negation values of the input boolean array values using the logical_not() function of the NumPy module −

# input boolean value
inputBool = False
 
# printing the input boolean value
print("Input boolean value:", inputBool)
 
# getting the negation of the input boolean value using logical_not() function
outputBool = np.logical_not(inputBool)

# printing the resultant boolean value
print("Output boolean value:", outputBool)

Output

On executing, the above program will generate the following output −

Input boolean value: False
Output boolean value: True

Conclusion

This article taught us 5 distinct methods for getting a boolean's negation in Python. We also learned how to convert any result, such as an expression or value, to a boolean type using the bool() method.