Logical Operators¶

We can use the logical operators (or Boolean Operators) and, or, and not to perform a certain kind of arithmetic on Boolean values. These rules for evaluating these operators are as follows:

When and appears between two Boolean values, it will evaluate to True if and only if both Boolean values are True. If either value is False, then the and operator will evaluate to False.
When or appears between two Boolean values, it will evaluate to True if either of the Boolean values are True. If both values are False, then the or operator will evaluate to False.
When not appears before a Boolean value, it will perform a logical negation, evaluating to the opposite Boolean value.

The cells below cover all of the possible cases that can arise from using these operators on Boolean values.

# Truth values for and operator
print(True and True)
print(True and False)
print(False and True)
print(False and False)

True
False
False
False

# Truth values for or operator
print(True or True)
print(True or False)
print(False or True)
print(False or False)

True
True
True
False

# Truth values for not operator
print(not True)
print(not False)

False
True

We can use the logical operators to combine basic conditional expressions into more complicated expressions.

x = 7
print( (x > 2) and (x < 9) )
print( (x > 2) and (x < 6) )

True
False

print( (x > 2) or (x < 6) )
print( (x > 9) or (x < 6) )

True
False

print( not (x < 9))

False

Python for Data Science

Logical Operators¶