Comparing values

Comparing values

Now that you have seen how to select branches based on a condition, you can learn more kinds of conditions to use. One common condition is a comparison between two values.

Inequality comparisons

Here are some examples of inequality comparisons and how to read them:

Inequality Code	Translation	Result
`2 < 3`	`2` is less than `3`	`True`
`1 > 400`	`1` is greater than `400`	`False`
`20 <= 30`	`20` is less than or equal to `30`	`True`
`50 >= 50`	`50` is greater than or equal to `50`	`True`

Inequalities with strings

You can also use inequality comparisons with strings. The comparison is based on the alphabetical order of the words.

Inequality Code	Translation	Result
`'alpha' < 'beta'`	`'alpha'` is less than `'beta'`	`True`
`'dog' >= 'doggy'`	`'dog'` is greater than `'doggy'`	`False`

Equality comparisons

Check if two values are the same with the double equal == syntax.

your_pet = 'dog'
my_pet = 'dog'
if your_pet == my_pet:
    print('Oh boy! We have the same kind of pet!')

A single equal symbol is an assignment, not a comparison. Python will warn you if you use the wrong symbol by providing a SyntaxError message like this:

>>> if 2 = 3:
  File "filename.py", line 1
    if 2 = 3:
         ^
SyntaxError: invalid syntax

You can also check if two values are not the same with the != syntax.

today = 'Thursday'
if today != 'Wednesday':
    print('Sadly, it is not hump day.')

Identity comparisons

You can check if two variables refer to the same object with the is syntax. When working with primitive data types, use == instead of is.

If you want to check if a variable is None, then you should use is.

if light_setting is None:
    print('The user has not chosen a light setting.')

Saving a comparison to a variable

Every comparison generates a boolean value, so you can assign that boolean to a variable.

birth_year = 2001
born_after_2000 = birth_year > 2000
if born_after_2000:
    print('You were born in the new millennium!')