DEV Community: Joseph Kariuki

VirtualenvWrapper & Python Virtual Environments

Joseph Kariuki — Mon, 06 Jun 2022 11:10:48 +0000

What is Virtualenvwrapper

It is a library containing extensions that support management of Python virtual environments and the workflow of development using these environments. Virtualenvwrapper enables Python developers manage multiple virtual environments, create, copy and delete these environments among other functionalities illustrated here.

Python Virtual Environments

There are many third-party Python libraries that are used by developers to achieve tasks and improve functionality of their software. Third-party libraries are simply code written by someone else rather than you and has probably been published to address a given problem and while developing you may require to leverage the functionality of that library. Also, these libraries are not part of the Python's Standard Library. Therefore, anyone who writes more than just a few lines of code or single script will more often than not find themselves making use of one or more of these libraries.

Installing Virtualenvwrapper

Virtualenvwrapper can be installed in some few steps that are illustrated in this section. The first step is to ensure that you have Python installed in your machine. If not, refer to these posts:
*Installing Python on Linux
*Installing Python on Windows
Also, you require to have pip, the Python's package index installed and likewise, if you do not have it, refer to this post:

Managing Python virtual environments

Linux

The official documentation recommends that virtualenvwrapper be installed in the same global-site packages as the virtualenv.
Log into your Linux machine and on the terminal install Virtualenvrapper using pip.

pip install virtualenvwrapper

To install it for your user only use the following command with --user statement to tell pip to install it for current user only.

pip install --user virtualenvwrapper

To confirm successful installation, one can use the whereis command to search the location of the virtualenvwrapper executable shell script that is usually installed with the library.

whereis virtualenvwrapper.sh

which should print out the location of virtualenvwrapper as shown below.

For the local user installation with the additional --user command, the output will appear as shown below.

To execute/run virtualenvwrapper, run the shell script that has been shown in the search.

source /usr/local/bin/virtualenvwrapper.sh

and depending on your installation the following error message may appear.

which simply complains that it cannot get the value for the VIRTUALENVWRAPPER_PYTHON variable and therefore as a quick fix, we have to set this in the terminal.
Check Python path using:

which python3

and copy the output of the above command as the value as shown below

VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3

hen re-run the source command

source /usr/local/bin/virtualenvwrapper.sh

which creates the virtual environment management command scripts as shown below. Note that your path may be different.

The virtualenvwrapper has successfully been set up for use.

Windows

There is a different library for virtualenvwrapper called virtualenvwrapper-win. Assuming that you already have installed Python in Windows, proceed with opening the Windows terminal or command prompt and install the package using pip.

pip install virtualenvwrapper-win

After installing, one can confirm installation using the pip list command which in this case shows the library/package and its dependencies that have been installed.

The virtualenvwrapper-win package has been successfully installed.

Common virtualenvwrapper commands

workon - Activate/deactivate and switch between multiple virtual environments.
mkvirtualenv - Create a new virtual environment.
mktmpenv - Create a temporary virtual environment.
rmvirtualenv - Remove an existing virtual environment
mkproject - Project directory management command for creating a new virtual environment in the preset (PROJECT_HOME) directory.
rmproject - Remove existing project.
lsvirtualenv - List all the environments.
deactivate - Deactivate an active virtual environment and switch back to global/system-based Python.

Add Virtualenvwrapper to Startup

1. Linux

After installing virtualenvwrapper successfully via pip, if you try executing any of the commands directly from the CommandPrompt or Powershell you will get an error.

To enable virtualenvwrapper to work on startup, a number a environment variables should be added either to the .bashrc or .profile scripts in the home directory of the user. This is because when system is started or rebooted, the OS begins with these.

VIRTUALENVWRAPPER_PYTHON - Overrides the $PATH search by setting the variable to the full path of the Python interpreter to use. In this specific case we'll set it to /usr/bin/python3
WORKON_HOME (optional) - This directs virtualenvwrapper on where to place the virtual environments which will be created. If not set it defaults to .local/share/virtualenvs/.
PROJECT_HOME - This directs virtualenvwrapper on where to place the project working directories. Note that this folder must be existing otherwise an error will be thrown. You can use your preferred editor to append the environment variables to the end of either .bashrc or .profile file. This is how the configuration done in .bashrc file appears in vim editor (yours may be different).

After appending, run the script otherwise you may have to re-log in or reboot to pick up the new variables which can be quite a hassle on time.

source ~/.bashrc

And any of the virtualenvwrapper commands can now be executed in the terminal. An illustration is shown below.

Note the brackets on the terminal prompt which indicates that we are in an active Python virtual environment. Now one can proceed with installing packages and developing their software or app.

2. Windows

After installing virtualenvwrapper-win successfully via pip, if you try executing any of the commands directly from the CommandPrompt or Powershell you will get an error.

PowerShell

CommandPrompt

Therefore, we should add the Python package scripts folder onto the Windows environment variables of the current user. The path to the scripts is usually located at C:\Users\<USERNAME>\AppData\Roaming\Python\Python310\Scripts in the case of Python 3.10. Use the following command to add the location to PATH. Remember to replace 'jkariukidev' below with your user.

setx PATH "%PATH%;C:\Users\jkariukidev\AppData\Roaming\Python\Python310\Scripts"

Restart Command Prompt or PowerShell and try to create a new virtual environment using mkvirtualenv command as illustrated below.

References

Python Virtual Environments - Python Documentation
Virtualenvwrapper - Python Package Index / Cheeseshop
Virtualenvwrapper-win - Python Package Index / Cheeseshop
Linux Environment variables - Ubuntu Documentation
Windows Environment Variables - Microsoft Documentation

Django - A Brief Introduction

Joseph Kariuki — Mon, 25 Apr 2022 07:13:05 +0000

What is Django?

Django is a robust Python web framework that was named after one Jean Reinhardt, who was a Roman-French jazz, guitarist and music composer and Django was his nickname according to Wikipedia.
Most of us know "Django Unchained" as the Tarantino movie that was released in 2012 and featured Jamie Foxx however, I am here to disappoint you since this post isn't about that. It is about a rich Python web framework that once you dip your fingers in it, you'll highly likely want to dip your hands and feet in it. Let us briefly unbolt Django.
Django can also be referred to as an Model-View-Template (MVT) framework used to build web applications.

Who uses Django

Websites that use Django framework include (but not limited to) the following:

Disqus This is a social website build on top of Django and other frameworks. It supports discussions, comments and audience activity analysis.
Instagram A social network platform currently owned by Meta (previously FaceBook) that supports media uploading, social account management and handles huge traffic and enormous amounts of data thanks to Django.
Spotify Music streaming and sharing platform that enables millions of subscribers around the world to listen, share and purchase music.
Bitbucket Cloud-based Git repository that hosts millions of code repositories and supports developer communities
Mozilla The code behind Mozilla website is based on Django project and serves very many diverse and independent pages with huge amounts of static and media content (images, JavaScript and Cascading Style Sheets).

Other Django powered websites include: Pinterest, Quora, The Onion and NASA Website

Why Django

Django framework is simple, yet sophisticated with a "batteries-included" approach which includes out-of-the box for mostly used functionalities such as the following:

Administrator user interface
Security and performance
Multiple database back end support
User authentication and by extension authorization
Rich REST API
Testing suite

I have recently deployed a simple Django website on Heroku that I developed from scratch demonstrating most of the above features. The live site resides at http://jkariukidev.herokuapp.com and the code base is on this repository. I have worked on a documentation to get you going by and it is still being improved.

There are many web frameworks out here but Django still remains that 'elephant in the room' when it comes to full-stack web development partly because of the rich features mentioned above and because; unlike micro-frameworks such as ExpressJS and Flask which yield more flexibility, Django surrenders flexibility and reduces opportunities for mistakes (and time spent in debugging the bugs associated with the mistakes) encountered in writing functionality code from scratch.

Django uses a Don't Repeat Yourself (DRY) principle which reduces code duplication.

Django includes a powerful Object Relational Mapper (ORM) layer by default that can be used to interact with various databases such as MySQL, SQLite, PostgreSQL and Oracle without having to rewrite the SQL dialect (language) code for each database back end since each database has its own dialect.

The Blues of Django

While Django is all good as a framework, there are some cons that come with it just like any other framework.

Django can be a bloated framework for small projects. It may not be the best approach for small projects like one page websites and the like. Preferable for projects such as blogs, social websites and e-commerce sites.
Monolithic architecture that limits developer's freedom in introducing new implementations outside Django. A workaround to this would include adding third-party packages into a Django project.
Full knowledge of the framework may be required to kick-start on projects and may take time to learn the whole framework.

References

Interested in learning Django? Here are some reference links to posts and some reads on the ever growing web development framework.

Reading GeoNode Data using QGIS

Joseph Kariuki — Wed, 20 Apr 2022 05:44:19 +0000

GeoNode data can be accessed using QGIS Desktop via the Open Geospatial Consortium (OGC) Web Services and GeoServer REST service. Here is a demonstration on the interoperability between GeoNode and QGIS as open source GIS softwares.

Installing Python3 in Linux

Joseph Kariuki — Tue, 29 Mar 2022 05:19:00 +0000

Introduction

Python3 has over the years increased in popularity among the developer communities worldwide and still is at the top according to this statistic. The language was authored by a Dutch programmer called Guido van Rossum.
Linux is an operating system like Windows and Mac-OS and one of the most popular platforms that power most cloud solutions and in fact, Android is also Linux under the hood. That said, we are going to see how one can get started with Python on Linux by installing it. This article assumes that the reader has some understanding in using Linux.

Why Python3?

Python is a high-level, open-source and dynamic programming language. It is generally easy to learn and code as compared to its other counterparts. Some of its features include:

Object-orientation: Python supports Object-Oriented programming concepts such as use of objects, classes, object encapsulation etc.
High-level language: unlike in low-level languages where one has to manage memory and remember the system architecture, in Python this is not necessary.
Interpreted language: Execution of Python's code is line-by-line at a time unlike in other programming languages like C++, Java and C. Python is easier to debug since there is no need for compilation.
Dynamically typed: The value of a variable is decided at run time rather than previous as it is with the case in statically typed languages like Java where one has to define a type (e.g. int, long, string). The above are just but a few mentions of the cool features of Python. Others include free and open source, high portability, can be integrated and interoperable with other languages e.g. C, Java and C#.

Uses of Python

Python is generally used in the areas of game development, data engineering, Artificial Intelligence, Machine Learning, graphical user interface (GUI) development and web development.

Game Development

Python can be employed in developing games and it can also act as a means of learning how to code with Python or deepening one's knowledge in the language. The libraries that can be leveraged for this include: arcade, pygame, Panda3D, cocos2D, pyglet, Python-ogre

Data Engineering

This entails data management methods such as data mining, modelling, crunching and metadata management ad different scales (from small data to big data). Python is primarily employed for data analysis and pipelines. Python libraries used here include:

Pandas, SciPy, Beautiful Soup

Artificial Intelligence / Machine Learning

According to IBM, Artificial Intelligence (AI) is technology that instructs computers to mimic the human mind in decision-making and problem-solving. Machine Learning (ML) is a subset of AI that consist of procedures that leverage on mathematical data models and algorithms to make predictions. Python implements ML and AI with generally fewer lines of code and pre-built libraries and being a scientific language also comes in support of these technologies. Some of the libraries used in AI and ML include:
Tensorflow, Scikit-Learn, Numpy, Keras, Theano

GUI Development

Python contains a variety of Graphical User Interface (GUI) frameworks that are being used by developers to create interactive windows and widget controls. The libraries include:
PyQt, Kivy, Tkinter and wxPython.
For a sneak peek on GUI development with PyQt, please refer to my GitHub repository on PyQt Interfaces and Desktop To-do list.

Web Development

Building, constructing, and maintaining websites is a broad definition of web development. A front-end, which communicates with the client, and a back-end, which contains business logic and interacts with a database, are typical components of web development. Python also supports quite a percentage of the total websites, web apps and software running in the world wide web. The libraries that are applied in web development include: Django, Flask, Pyramid and Turbogears and Web2Py

Methods of Installing Python3

Enough of the libraries, features and usage of Python. Let us see how we can successfully install Python3 in Linux. In this article, we are using Ubuntu 20.04 Long Term Release (LTS) distribution of Linux. I have compiled three different approaches that include:

Using deadsnakes PPA
Building from source

Installing via Apt and deadsnakes PPA

Most factory versions of Ubuntu ship with Python already installed. To confirm if Python is already installed in your OS, enter the following command:

python --version

If python is not installed, the following output will be shown.

The recommended Python is 3.7.x and above therefore if lower than the version or not installed, continue to the next step. Let us first update and upgrade the repository lists via the following command:

sudo apt update && sudo apt upgrade

Then install the software-properties-common package whose work is to allow one to easily manage distributions and independent software vendor software sources.
The next step is to add the deadsnakes PPA with the following command

add-apt-repository ppa:deadsnakes/ppa

which shows the following prompt to press enter.

Press enter to proceed and once it is through you should refresh the package list once again via

apt update

then install Python 3.10 (latest as of the time of this publication) via the following command.

apt install -y python3.10

Assuming successful installation of Python 3.10, check the specific version via:

python3.10 --version

which shows the specific version.

Building Python from Source

Packages and software can be installed by compiling from downloaded binary scripts and Python is no different. We shall begin by installing the prerequisites required for compiling and building Python which include:

Installing required packages
Building Python from source
Installing Python

Installing required packages

To install the pre-requisites, enter the following command.

apt install -y build-essential checkinstall libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev

Build Python

To build Python, the first step should be to download the Python version of your choice (3.10.04 used here). I am making use of the wget utility package to download from Python website.

wget https://www.python.org/ftp/python/3.10.4/Python-3.10.4.tar.xz

Extract the downloaded Python archive when download is complete. One can add the v option for verbose logs when extracting e.g.add -xvf in place of -xf below.

tar -xf Python-3.10.4.tar.xz

Navigate into the Python directory and configure and ensure enable-optimization option is added as shown in the command below.

cd Python-3.10.4
./configure --enable-optimizations

Install Python

To install Python without overwriting the default version that is already installed in Ubuntu, use the following command. Note, if you use make install it shall overwrite the default Python and may cause some issues ahead.

make altinstall

To test Python installation, use the same command as in the previous steps.

python3.10 --version

Conclusion

We have been able to install the latest Python in Ubuntu 20.04 using various methods. To install Python on Windows, please refer to my previous post here.

HAPPY CODING!!!

GeoNode Basic Installation on Windows

Joseph Kariuki — Wed, 23 Mar 2022 02:17:51 +0000

Harness the capabilities of Geospatial Information, DevOps and Windows Subsystem for Linux in deploying GeoNode Spatial Data Infrastructure in Windows in just a few steps illustrated below.

GeoNode Basic Installation using Docker

Joseph Kariuki — Wed, 16 Mar 2022 02:30:53 +0000

GeoNode is an open-source spatial data infrastructure (SDI) that is open source and used to store and manage geospatial data including sharing it over the web.

Docker came to revolutionize the DevOps practices and here is one example of such. Let us deploy GeoNode in Ubuntu 20.04 using docker.

GeoNode Advanced Installation In Ubuntu 20.04 Part3

Joseph Kariuki — Wed, 09 Mar 2022 02:19:12 +0000

This is a continuation of the second steps in practical installation of GeoNode in Ubuntu 20.04 using advanced method.

GeoNode is an open-source spatial data infrastructure (SDI) that is open source and used to store and manage geospatial data including sharing it over the web.
In this tutorial we install and configure PostgreSQL/PostGIS and GeoServer components of GeoNode.

GeoNode Advanced Installation In Ubuntu 20.04 Part2

Joseph Kariuki — Sat, 05 Mar 2022 01:42:09 +0000

This is a continuation of the First steps in practical installation of GeoNode in Ubuntu 20.04 using advanced method.

GeoNode Advanced Installation in Ubuntu 20.04 Part 1

Joseph Kariuki — Fri, 25 Feb 2022 02:37:17 +0000

This is the First steps of the installation of GeoNode in Ubuntu 20.04 using advanced method.

GeoNode is an open-source spatial data infrastructure (SDI) that is open source and used to store and manage geospatial data including sharing it over the web.

In this tutorial we install and configure the pre-requisites of GeoNode.

Creating Python Virtual Environment with Pip

Joseph Kariuki — Sat, 20 Nov 2021 10:33:54 +0000

There are two known Python versions;

Python2 that got deprecated in the beginning of 2020.
Python3 that is being used currently in many projects.

A requirement is that when installing Python in Windows, ensure that you have checked the "Add to PATH" checkbox otherwise Python and pip commands will not be executed in the Command Prompt.
For instructions on installing Python in Windows, refer to my post here.

Python Virtual Environment

By default, Python installs modules or packages system wide which can become an issue if he program(s) in use or being developed or tested require different versions of the same module. A Python virtual environment is comes into use for the above mentioned challenge and can be defined as a self-contained directory tree that hosts a Python installation and some given packages. For more on definition of it refer to Python documentation

Pip

Python versions 2.7.9 / 3.4 and above have pip shipped in their installers therefore one doesn't have to install pip separately. However for earlier versions, reference can be made to the following link
Pip is a package management system for Python that can also be used to install various software written in Python / modules and their respective dependencies.

Install pip in Windows

To install pip in Windows, ensure that you click on 'Customize installation' option shown below and then check the checkbox labelled 'install pip'.

check the checkbox labelled 'pip' as shown below.

Check pip

It is always good practice to ensure that pip is installed and working as it should before taking the next steps. To check pip installation in Windows, open Command Prompt (CMD) or Windows Terminal and type the following command and note that the letter 'V' is in upper case.

pip -V

which should output the version and path to the location of it as shown below.

After confirming the installation, the next step will be to install virtual environment package.

Installing virtualenv package

We can now use pip to install virtualenv package and for this we shall install it system-wide using the following command that one can paste inside CMD/terminal.

python -m pip install virtualenv

Ensure the PC is connected to the internet so as to download the packages and their dependencies. The installation appears as shown below.

If you get the warning (shown in amber) that indicates you need to upgrade pip, then run the following command to upgrade pip to the latest version.

python -m pip install --upgrade pip

The upgrade process in the command window appears as shown below. The pip version has been upgraded from version 21.2.3 to 21.3.1.

Creating Virtual Environment

Let us create a virtual environment by running the following command in the CMD.

python -m virtualenv my_env

The above command creates a new python virtual environment named my_env in the current directory. The creation process appears as shown below.

The folder that has been created appears as shown below. We won't go into the details of the folder otherwise if interested, refer to the Python pip documentation.

The next step will be to activate the just created virtual environment.

Activating the Virtual Environment

To use the virtual environment, it has to be activated otherwise if not, one will be using the system-wide pip which is not recommended and may lead to dependency issues. To activate the virtual environment run the following command.

my_env\Scripts\activate

which enters into an active environment denoted by the name in the parentheses as shown below.

To test the environment run the previously run command for checking the pip version, pip -V command which will show the version and location of pip shown below. Note the location is different from the pip that is system-wide.

To check on the installed packages run the following command.

pip list

which will show all the packages that are installed and these are the default packages.

To show the details of a package for instance, pip package which exists in the current virtual environment, type the following command in the command line.

pip show pip

which displays some information about the package as shown below.

The last command will be for checking outdated packages which can be done by running the following command.

pip list -o

which shows the package name, current and latest version.

Conclusion

Pip and virtualenv can be used to create and manage isolated environments and python projects alike and are actually being utilized a lot. Therefore it would be of great importance to learn about them by referring to the following:

Pip documentation
Python Virtual Environments and Packages To close, one has to deactivate the environment by running the following command.

deactivate

and this will return to the usual commandline without the environment name inside the parentheses.
Keep posted for future posts on virtual environments and subscribe to my posts as well.

Installing Python3 in Windows10

Joseph Kariuki — Sat, 09 Oct 2021 15:37:53 +0000

Introduction

This post is a walkthrough for those who want to begin coding in Python and probably do not know how to install the software in order to get started on coding with it.

Step1: Downloading Python

Navigate to the official Python download page in your preferred browser here and it may look similar to the one shown below.

Click on the download button to download the latest version of Python (Python 3.10 in this post) otherwise you can scroll down to check other specific versions that you prefer. The download process should start and give it some moments to complete.
Once the download is complete, the installer file should appear as shown below. Ensure to download Python that corresponds to your machine whether it is 32-bit or 64-bit and for details on that refer here

Step2: Installing Python

Double click the installer to run and at this point ensure that the logged in user has administrative rights (running and installing Python may require this). The setup wizard should appear as shown below. Ensure the 'Add to PATH' checkbox is checked as shown in the screenshot below.

Click 'Install Now' to proceed with the installation process which shall be indicated with a green progress bar as shown below. Give it some moments to complete installing.

Once the installation is complete, an installation success wizard page appears as shown below otherwise if there is an installation error a different message will appear.

To close the installation wizard, click Close button. To confirm that Python has been installed to Windows PATH, open the Windows Command Prompt (CMD) by clicking on the Start button and typing 'cmd' text as shown below.

Step3: Running Python

Click on the 'Command Prompt' option and a black window should show up as below which is the Windows Command Prompt that is similar to the Linux Terminal

Type 'python' in the Command Prompt and click Enter key on the keyboard and the Python shell should appear as shown below indicating that Python has been installed and added to Windows PATH.

To exit the Python shell, type 'exit' command and click Enter key on the keyboard. Now, Python has been installed successfully in Windows.

HAPPY CODING!!!

Firing up that coding journey

Joseph Kariuki — Sat, 09 Oct 2021 14:44:04 +0000

Have you found yourself interested in programming or are you in another field or career and have been considering to switch into coding?
Well, I had a similar experience some years ago (2016) and while at it made a decision to embrace coding which wasn't a big part of my job then.
I used to write some short code snippets in Python and JavaScript and play around with HTML and CSS (they are not programming languages but equally important in my view). Browsing through the internet and checking out the projects that other people were doing inspired me to start the coding journey.
I started by doing some HTML, CSS and JavaScript tutorials on https://www.codecademy.com/ where I learned some cool basic stuff on the subjects.
I then embarked on FreeCodeCamp which one can visit at https://www.freecodecamp.org/ where I also proceeded to learn on HTML, CSS and JavaScript.
For beginners and newbies, I would highly recommend the platforms and you are not limited to them since currently there are many others including YouTube channels.
Well, happy coding and keep sharing your progresses and project paths.