How to import a library in Python – with example

How to import a library in Python?
How to import a library in Python – basics
How to import a library in Python – importing specific items in a module
How to import a library in Python – importing modules as an alias
Summary
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How to import a library in Python?

In Python, libraries are used to refer to a collection of modules that are used repeatedly in various programs without the need of writing them from scratch.

Modules on the other hand refer to any Python file saved with the .py extension. Modules often contain code such as functions, classes and statements that can be imported and used within other programs.

In this article, we’ll show you how to import a library in Python step by step.

Besides built-in functions that we can use such as the print function, we can also use built-in modules to build more sophisticated programs.

How to import a library in Python – basics

We can also create our own modules that we can reuse in other programs. We can import and use modules across different programs using keyword import.

Modules in the Python standard library need no installing and therefore importing them at the top of our programs is enough to get started.

Modules provided in the standard library provide us with access to system functionality among other standard solutions.

A common example of such libraries is the math library. The math library provides access to common mathematical functions.

Using these functions we can perform various mathematical expressions such as finding the square root of a number.

Libraries not provided in the standard library need to be installed first. Once they have been installed in our system we can then proceed to import them into our programs.

There are a number of ways we can install various libraries, some of the common ones is the use of the pip package manager.

Although pip is installed by default in versions of Python later than 3.4, it can also be installed using the command:

pip install pip

Pip allows us to install packages from indexes such as the Python Package Index. One of the most commonly installed and used libraries in python is the requests library.

The request library is the defacto for making HTTP requests in Python. It is installed by running the command below.

pip install requests

If the request library is already installed in your system you’re likely to get the message that the requirement is already satisfied. Otherwise, the requests library will be installed automatically.

How to import a library in Python – importing specific items in a module

Using the keywords from…import we can import specific items from a library or module. These may include functions or classes within that specific library.

This is important especially when you do not intend to use only a specific function in a module and therefore it is needless to import the entire module.

For instance, in the example below instead of importing the entire random module, we are just importing the specific function that we can use to create a random integer within a certain range as shown below.

from random import randint

This is an alternative method to using the dot notation in accessing various elements in a module.

How to import a library in Python – importing modules as an alias

Python allows us to change the names of modules and functions and name them as we want. This is useful in scenarios where a module may have taken up a certain name and we want to use a different one.

It is also convenient when a module has a very long name and rewriting that name throughout the program is inconvenient and may cause some bugs due to misspelling.

The name given to the module or library in place of the original name is known as the alias. In the example below we are importing the random library as an alias.

Some libraries such as the pandas, NumPy libraries have de facto alias names. In such a case it is advisable that we stick to the common practice of aliasing these libraries as such.

import pandas as pd
import numpy as np

Summary

Those are the basic methods and modules that you need to know if you’d like to learn how to import a library in Python.

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