Overview

Teaching: 20 min
Exercises: 10 min

Questions

• How can we make comparisons between values in Python?

• Truey-ness in Python - what do we mean by True and False?

Objectives

• Be able to perform basic comparisons in Python

• Understand what True and False can refer to in Python

Key Points

• Booleans are used to reflect the truthiness of a statement in Python.

• Other than the output of comparisons, booleans are also used to refer to special values (typically empty values)

Learning outcomes

By the end of this lesson, you will be able to:

1. Use Python’s comparison operators (>, <, >=, <=, ==) to test values.
2. Distinguish between assignment (=) and equality (==).
3. Recognize how Python uses True, False, and truthy/falsy values to control program flow.

Comparisons in Python

Comparisons are a central component of prgrams, and are used extensively to control program flow. Comparisons are performed in Python in a manner similar to how we will write them in mathematics:

35.2 > 35    # True
35.2 >= 35   # True
35.2 < 35    # False
35.2 == 35.2 # True

Equalities in Python

You will notice that we used == to compare whether two values are equal. A common mistake people make is to use =, which means something else in Python (and most programming langauges). What does = do?

While mathematical comparisons (>, <, <=, >=) can only used used for numeric data types (including dates), the equality test (==) can be used on most data types, including strings, lists, and dictionaries. For example:

[1,2,3] == [1,2,3]  # True
"abc" == "bca"      # False

Try this

# TODO: Fill in the blanks
# Create two dictionaries
dictionary1 = __"name": "jeremy"__
dictionary2 = __"name": "jeremy"__
dictionary1 __ dictionary2         # True

Membership tests

Another class of comparison is that of membership testing. For instance, lets say we have a list of fruits as such:

fruits = ['apple', 'orange', 'banana', 'kiwi']

It is a relatively common task to ask if a specific value is in the list (or a string, for that matter). We can quicky do this using the in operator. Likewise, negation can be done by adding the not operator. For instance:

fruits = ['apple', 'orange', 'banana', 'kiwi']
"apple" in fruits         # True
"pineapple" in fruits     # False

"pineapple" not in fruits # True

"apple" in "pineapple"    # True
"pineapple" in apple      # False

Note that in test of membership, casings matter. For instance,

"apple" in "pineapple" # True
"apple" in "pineApple" # False

How do I do this?

We have seen how "apple" in "pineapple" is True, but"apple" in "pineApple" is False. This is by design. However, what can you do if you want to "apple" in "pineApple" to also be True?

🟢 True or False?

When we do a comparison in Python, we will get either True or False in Python. These special values are called boolean types. While True and False can refer to whether a comparison is true or otherwise, Python takes this further with a concept called truthiness. This refers to how certain special values are also considered True or False. Specifically, empty lists, empty tuples, empty dictionaries and zero will evaluate to False.

Try this

Try to check the above statement about truthiness in Python using the following examples:

print (bool(0)) # False
print (bool(1)) # True
# TODO: Test the truthiness of an empty string, an empty list and an empty dictionary

Conclusion

Comparisons and boolean logic are the backbone of decision‑making in programming. In this secion, we have learned how to compare numbers, strings, and even collections, and how Python interprets results as True or False. With truthiness, Python goes a step further, letting you write clean, natural conditions without extra checks. In the next section, you’ll see how these building blocks let us guide the logic of entire programs.