The Python *not equal to* (`left!=right`

) operator returns `True`

when its `left`

operand is not equal to its `right`

operand as defined by the `__ne__()`

magic method. Otherwise, it returns `False`

. For example, `3!=2`

evaluates to `True`

, but `3!=3`

evaluates to `False`

.

## Examples

Let’s explore a couple of examples regarding the *not equal to* operator.

Is 3 not equal to 2?

>>> 3 != 2 True

What about `'h'`

not equal to `'h'`

?

>>> 'h' != 'h' False

Can you compare collections such as lists, strings, tuples?

>>> [1, 2] != [1, 2] False >>> [1, 2] != [1, 2, 3] True >>> (1, 1) != (1, 1, 1) True >>> 'hello' != 'hello!' True

Yes!

The list *not equal to* operator iterates over the lists and checks pairwise if the i-th element of the left operand is different to the i-th element of the right operand.

Can you use the *not equal to* operator on custom objects? Yes!

## Python Not Equal to on Custom Objects

To use the* not equal to* operator on custom objects, define the `__ne__()`

“dunder” *magic method *that takes two arguments: `self`

and `other`

. Use attributes of the custom objects to determine if an object is not equal to another. The return value is a Boolean `True`

or `False`

.

In the following code, you check if a Person is not equal to another Person by using the `age`

attribute as a decision criterion:

class Person: def __init__(self, age): self.age = age def __ne__(self, other): return self.age != other.age alice = Person(18) bob = Person(19) carl = Person(18) print(alice != bob) # True print(alice != carl) # False

Because Alice is 18 years old and Bob is 19 years old, the result of `alice != bob`

is `True`

. But the result of `alice != carl`

evaluates to `False`

as both have the same age.

## Python Not Equal to Multiple Values

**How to check that a variable is not equal to multiple variables?**

To check whether a variable is not equal to multiple values given in a list, use the

membership operator. For example, the expression **not in**`'Alice' not in ['Ann', 'Bob', 'Carl']`

returns `True`

if the string `'Alice'`

is not in the given list, and `False`

otherwise.

The following example creates a list of three values and stores it in the variable `negatives`

. You then check if a query string `'Alice'`

is not equal to the elements stored in the list `negatives`

. If so, it prints `'Yay!'`

to the shell:

negatives = ['Ann', 'Bob', 'Carl'] if 'Alice' not in negatives: print('Yay!')

The output is:

Yay!

## Python Not Equal to 0

To check if a variable x is not equal to the value 0, use the expression

. In a Boolean context such as an if condition environment, you can also use the expression **x != 0**

instead of **if x:**`if x != 0:`

because Python implicitly transforms each 0 value into a Boolean `False`

, and each other value into `True`

.

Here are both semantically-identical methods:

x = 42 # Method 1 if x != 0: print('yes') # Method 2 if x: print('yes')

The output of the code snippet is:

yes yes

## Python Not Equal to NaN

To check whether a number `x`

is not equal to NaN, use the

expression that returns **not math.isnan(x)**`True`

if the number `x`

is not NaN, and `False`

otherwise.

The following code shows an example where we first create a NaN float value using the `float('nan')`

built-in method, and then checking that number using `math.isnan(x)`

. The result is `False`

because the value is, indeed, not a number.

import math x = float('nan') print(not math.isnan(x)) # False

## Comparison Operators

Comparison operators are applied to comparable objects and they return a Boolean value (`True`

or `False`

).

Operator | Name | Description | Example |
---|---|---|---|

> | Greater Than | Returns `True` if the left operand is greater than the right operand | `3 > 2 == True` |

< | Less Than | Returns `True` if the left operand is smaller than the right operand | `3 < 2 == False` |

== | Equal To | Returns `True` if the left operand is the same as the right operand | `(3 == 2) == False` |

!= | Not Equal To | Returns `True` if the left operand is not the same as the right operand | `(3 != 2) == True` |

>= | Greater Than or Equal To | Returns `True` if the left operand is greater than or equal to the right operand | `(3 >= 3) == True` |

<= | Less Than or Equal To | Returns `True` if the left operand is less than or equal to the right operand | `(3 <= 2) == False` |

While working as a researcher in distributed systems, Dr. Christian Mayer found his love for teaching computer science students.

To help students reach higher levels of Python success, he founded the programming education website Finxter.com that has taught exponential skills to millions of coders worldwide. He’s the author of the best-selling programming books Python One-Liners (NoStarch 2020), The Art of Clean Code (NoStarch 2022), and The Book of Dash (NoStarch 2022). Chris also coauthored the Coffee Break Python series of self-published books. He’s a computer science enthusiast, freelancer, and owner of one of the top 10 largest Python blogs worldwide.

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