Python Bits and Bobs

Last updated on 2026-06-23 | Edit this page

Estimated time: 12 minutes

Overview

Questions

What are some elements of python that are not covered in beginner courses but are still useful to know?

Objectives

Bits and Bobs

There are some elements of python that are fundamental elements of the language, but that are not typically covered in beginner courses, either because they are not strictly necessary to know to get started with programming, because they are only useful in edge cases, or because they are simply shorthand ways of doing things that are already possible in other ways. In this episode, we will cover some of these elements, and how they can be useful in your own code.

Tuple Unpacking

Tuple unpacking is a feature in Python that allows you to assign values from a tuple (or any iterable) to multiple variables in a single statement. This can make your code more readable and concise, as long as you use it responsibly.

Here’s an example of tuple unpacking in action:

PYTHON

# Without tuple unpacking
geo_coordinates = (50.4651, 6.03548)
latitude = geo_coordinates[0]
longitude = geo_coordinates[1]

# With tuple unpacking
latitude, longitude = geo_coordinates

It can also be used to unpack values from a function that returns multiple values:

PYTHON

def get_coordinates():
    return (50.4651, 6.03548)

latitude, longitude = get_coordinates()

It’s a great shorthand, but keep in mind that it can make your code less readable if overused or used in complex situations.

Asterisk Unpacking

As a bonus, you can also use an asterisk * to unpack the remaining values of a tuple into a list:

PYTHON

geo_data = (50.4651, 6.03548, 100, 200, 300)
latitude, longitude, *other_values = geo_data

Or the double asterisk ** to unpack the remaining values of a dictionary into another dictionary:

PYTHON

geo_data = {"latitude": 50.4651, "longitude": 6.03548, "altitude": 100, "speed": 200}
latitude, longitude, **other_values = geo_data

*args and **kwargs

You might have seen the *args and **kwargs syntax in function definitions before. These are used to allow a function to accept an arbitrary number of positional and keyword arguments, respectively. This can be useful when you want to create a function that can handle a variable number of inputs, or when you want to pass arguments to another function without knowing in advance how many arguments will be passed.

PYTHON

def make_a_pizza(size, **kwargs):
    print(f"Making a {size} pizza")
    add_toppings(**kwargs)

def add_toppings(**toppings):
    for topping, amount in toppings.items():
        print(f"Adding {amount} {topping}")

make_a_pizza("large", mushrooms=10, salami=8, green_peppers=5)

`zip` and `enumerate`

We can iterate over a dictionary using a for loop like this:

PYTHON

my_dict = {'a': 1, 'b': 2, 'c': 3}
for key, value in my_dict.items():
    print(key, value)

This works because the items() method of a dictionary returns an iterable of key-value pairs. The zip function is a built-in function that allows you to iterate over multiple iterables at the same time. It takes two or more iterables as arguments and returns an iterator that produces tuples containing the corresponding elements from each iterable.

PYTHON

x_values = ["a", "b", "c"]
y_values = [1, 2, 3]

for x, y in zip(x_values, y_values):
    print(x, y)

The enumerate function is related, as it allows you to iterate over an iterable while keeping track of the index of the current item. It takes an iterable as an argument and returns an iterator that produces tuples containing the index and the corresponding item from the iterable.

PYTHON

my_list = ['a', 'b', 'c']
for index, value in enumerate(my_list):
    print(index, value)

Membership Testing

The keyword in can be used to quickly check if an element is present in a list, tuple, set, or dictionary. This can be useful for checking if a value exists in a collection without having to write a loop or use a more complex method. Here’s an example:

PYTHON

toppings = ["pepperoni", "mushrooms", "green peppers"]

if "mushrooms" in toppings:
    print("Mushrooms are available!")
else:
    print("Mushrooms are not available.")

Chained Comparison Operators

What if we have a situation where we want to check if a number is between two other numbers? We could use something like this:

PYTHON

my_number = int(input("Please enter a number: "))
if 10 < my_number and my_number < 20:
    print("Good!")
else:
    print("Not good!")

but a more elegant way to do this is to use chained comparison operators:

PYTHON

my_number = int(input("Please enter a number: "))
if 10 < my_number < 20:
    print("Good!")
else:
    print("Not good!")

This is both shorter and more readable.

`any` and `all`

The built-in functions any and all can be used to check if any or all elements of an iterable are true, respectively. This can be useful for checking if a list of conditions are met without having to write a loop to check each condition individually. Here’s an example:

PYTHON

available_toppings = ["pepperoni", "mushrooms", "green peppers"]

pizza1_toppings = ["pepperoni", "mushrooms"]
pizza2_toppings = ["pepperoni", "pineapple"]

can_make_pizza1 = all(topping in available_toppings for topping in pizza1_toppings)
can_make_pizza2 = all(topping in available_toppings for topping in pizza2_toppings)

print(f"Can make pizza 1: {can_make_pizza1}")  # Output: True
print(f"Can make pizza 2: {can_make_pizza2}")  # Output: False

String Formatting

We have a couple options for formatting strings in Python:

format()

PYTHON

topping, price = "mushrooms", 1.50
formatted_string = "The price of {} is ${:.2f}".format(topping, price)
print(formatted_string)  # Output: The price of mushrooms is $1.50

f-strings

PYTHON

topping, price = "mushrooms", 1.50
formatted_string = f"The price of {topping} is ${price:.2f}"
print(formatted_string)  # Output: The price of mushrooms is $1.50

sprintf-style formatting

PYTHON

topping, price = "mushrooms", 1.50
formatted_string = "The price of %s is $%.2f" % (topping, price)
print(formatted_string)  # Output: The price of mushrooms is $1.50

Callout

The “.2f” part specifies that this number should be formatted as a floating-point number with 2 decimal places. You can also use other format specifiers, such as “,.d” for integers with commas as thousands separators, or “e” for scientific notation.

`_` as a throwaway variable

You might sometimes see the underscore _ used as a variable name in Python. This is a convention that indicates that the variable is a “throwaway” variable, meaning that it is not going to be used later in the code. This can be useful when you need to unpack a tuple or list in a loop, but you don’t care about one of the values. Here’s an example:

PYTHON

for _, value in enumerate(["a", "b", "c"]):
    print(value)

Challenge

Challenge: Swapping Values

We can use tuple unpacking to swap the values of two variables without needing a temporary variable. Take the following code that swaps the values of a and b:

PYTHON

a = 23
b = 42

temp = a
a = b
b = temp

Can you rewrite this code without using the temp variable, using tuple unpacking instead?

Show me the solution

PYTHON

a = 23
b = 42

a, b = b, a

Challenge

Challenge: Checking User Input

We have a small script that asks the user for a series of words that are longer than 4 characters but shorter than 10 characters. Additionally we want to make sure that none of their words are in the banned list. Use the all and any functions to complete the following code:

PYTHON

banned_words = ["hunter2", "secret", "turtle"]

user_words = input("Please enter a series of words, separated by spaces: ").split()

# Check that words are longer than 4 characters and shorter than 10 characters
valid_length = # Your code here

# Check that none of the words are in the banned list
not_banned = # Your code here

if valid_length and not_banned:
    print("All words are valid!")

Show me the solution

PYTHON

banned_words = ["hunter2", "secret", "turtle"]

user_words = input("Please enter a series of words, separated by spaces: ").split()

# Check that words are longer than 4 characters and shorter than 10 characters
valid_length = all(4 < len(word) < 10 for word in user_words)

# Check that none of the words are in the banned list
not_banned = all(word not in banned_words for word in user_words)

if valid_length and not_banned:
    print("All words are valid!")

Challenge

Challenge: Parse the Sensor Data

We have a sensor that is sending us data. Our colleague has already written some code to parse part of the data, but needs help to parse the rest of it. The data is in the following format:

PYTHON

sensor_data = "humidity,pressure,altitude:65%,129mb,103m"
measurements = sensor_data.split(":")[0].split(",") # Get a list of the measurement names
values = sensor_data.split(":")[1].split(",") # Get a list of the measurement values

We would like to print out the formatted measurements and their values like this:

Humidity: 65%
Pressure: 129mb
Altitude: 103m

Give me a hint

Use the zip function to combine the measurements and values lists

Give me a hint

Use tuple unpacking in a for loop to pull out the measurements and values from the zipped list.

Show me the solution

PYTHON

for measurement, value in zip(measurements, values):
    print(f"{measurement.capitalize()}: {value}")

For good measure, we also use the capitalize() method to capitalize the first letter of each measurement name.

Challenge

Challenge: Use Chained Comparison Operators

Rewrite the following code using chained comparison operators:

PYTHON

temperature_outside = 34
temperature_inside = 29

if temperature_outside > 30 and temperature_inside < 25:
    print("It's hot outside, but cool inside.")
elif temperature_outside < 25 and temperature_inside > 30:
    print("It's cool outside, but hot inside.")
elif temperature_outside > 30 and temperature_inside > 30:
    print("It's hot everywhere.")
else:
    print("It's probably a nice day.")

Show me the solution

Note that chained comparison operators only work when something is in a range. So while we can use them for the first two conditions, we cannot use them for the third.

PYTHON

if temperature_outside > 30 > temperature_inside:
    print("It's hot outside, but cool inside.")
elif temperature_outside < 25 < temperature_inside:
    print("It's cool outside, but hot inside.")
elif temperature_outside > 30 and temperature_inside > 30:
    print("It's hot everywhere.")
else:
    print("It's probably a nice day.")

Key Points

Python Bits and Bobs

Overview

Questions

Objectives

Bits and Bobs

Tuple Unpacking

PYTHON

PYTHON

Asterisk Unpacking

PYTHON

PYTHON

*args and **kwargs

PYTHON

zip and enumerate

PYTHON

PYTHON

PYTHON

Membership Testing

PYTHON

Chained Comparison Operators

PYTHON

PYTHON

any and all

PYTHON

String Formatting

PYTHON

PYTHON

PYTHON

_ as a throwaway variable

PYTHON

Challenge: Swapping Values

PYTHON

Show me the solution

PYTHON

Challenge: Checking User Input

PYTHON

Show me the solution

PYTHON

Challenge: Parse the Sensor Data

PYTHON

Give me a hint

Give me a hint

Show me the solution

PYTHON

Challenge: Use Chained Comparison Operators

PYTHON

Show me the solution

PYTHON

`zip` and `enumerate`

`any` and `all`

`_` as a throwaway variable