Python Functions and Modules

With this third article, let's continue our series on learning Python, our first programming language. This article will discuss Python functions and modules and how they can help us organize and reuse our code.

Functions

A function in Python is a section of code that you can run several times with various input values. Functions can accept one or more arguments as input and are defined using the "def" keyword. A function's fundamental syntax is as follows:

def function_name(arg1, arg2, ...):

    # code to execute

    return output

For example, the following code defines a function named "add" that takes two arguments and returns their sum:

def add(x, y):

    return x + y

We can call this function by passing in the required arguments like this:

result = add(3, 4)

print(result)  # prints 7

For some parameters, functions can also have default values, which means that if you omit the argument when invoking the function, you use the default value.

def greet(name, greeting="Hello"):

    print(f"{greeting}, {name}")

greet("John") # prints "Hello, John"

greet("Jane", "Hi") # prints "Hi, Jane"

The f in f" {greeting}, {name}" stands for "format." It is used to indicate that the string is an f-string. F-strings allow us to include expressions inside string literals, enclosed in curly braces {}, which will be evaluated at runtime. The result of the evaluated expression is then formatted and included in the final string.

In the example provided, the f-string f" {greeting}, {name}" is used to insert the values of the greeting and name variables into the string, and it will produce the final string that is passed to the print function.

In this case, when we call the function with greet("John"), the greeting variable will be the default value of "Hello," and the name variable will be "John," so the f-string will be evaluated, passed, and printed as "Hello, John."

Modules

A file containing definitions and statements in Python is known as a module. Variables, classes, and functions can all be defined in a module. A module may also include code, and the import statement is used to import the modules. For instance, the code below imports the math module and makes use of its sqrt function to determine the square root of a number:

import math

x = math.sqrt(16)

print(x)  # prints 4.0

We can also import specific functions or variables from a module using the "from" and "import" keywords.

from math import sqrt

x = sqrt(16)

print(x)  # prints 4.0

Additionally, we can use the "as" keyword to give an alias to a module or function while importing it.

import math as m

x = m.sqrt(16)

print(x)  # prints 4.0

Conclusion

We've discussed Python functions and modules in this piece and how to utilize them to organize and reuse our code. We learned how to import and use modules and define and call functions. We may isolate specific functionality using functions, which also helps to make our code more legible and modular. The following post will discuss using Python for data analysis and visualization.