Functional Programming in Python for Network Engineers

There are many types of programming languages. As an example, there are Procedural programming languages like Pascal, C, etc while there are Declarative languages like SQL and there are Object Oriented languages like Java. Python is a type of Functional programming language which does support Object Oriented Programming.

Comprehensions

This means to a concise way to create collections like Lists, Dictionaries, or Sets using a single line of code. Following example will explain what it is practically.

Following code captures the Gig interfaces in the traditional way..

Following code will give the same output and it is more Pythonic..

Single line covers it, there are actually 3 sections, let's break it down.

If we read the sections like the way I have numbered above, it is more understandable.

Note:- If we want to get the output in some modified way, as an example in block letters, we can use int.upper() to replace just int which is the expression.

Following example shows how Comprehension works for a Dictionary which outputs the routers which are up.

Lambda Function

A Lambda function in Python is a small, anonymous function defined using the lambda keyword. It's often used for short, simple operations and also called throw away functions after use.

Following example shows a Lambda function which adds 2 given values in single line of code.

Following is another one which compares a given number with 5 to check greater than or lesser.

Map Function

The map() function in Python applies a function to every item of an iterable (like a List) and returns a map object (which you can convert to a list, tuple, etc.).

Syntax is like the following..

map(function, iterable)

Note:- x**2 is the way to get square, double multiply..




Output will be;

Filter Function

The filter() function in Python is used to filter elements of an iterable (like a List) based on a function that returns True or False.

Syntax is like the following..

filter(function, iterable)

Note:- % checks the remainder..

Output will be;

Reduce Function

The reduce() function in Python is used to apply a function cumulatively to the items of a sequence, reducing the sequence to a single value.

Syntax is like the following..

reduce(function, iterable)

What this gives is the multiplication of all the values together. 1x2 = 2 then 2x3 = 6 then 6x4 =24 and finally 24x5 = 120

Note:- reduce should be imported from functools library

Here is another example of reduce() function

Note:- " " in the Lamba function is to make the space and the result will be like the following..