DEV Community: Joshua Wainaina

Creating a Knowledge Graph with Drupal Content

Joshua Wainaina — Sun, 02 Aug 2026 20:59:32 +0000

Introduction

Managing content efficiently becomes more difficult as Drupal websites grow. Traditional content management structures information in discrete entities but often does not expose meaningful relationships between them. A knowledge graph solves this, connecting content like nodes, taxonomy terms, users and media into an intelligent network. This facilitates semantic search, personalized recommendations and AI-driven applications to enhance how users discover and engage with content.

Knowledge Graphs Explained

A knowledge graph is a structured representation of linked information. It links related entities by relationships instead of storing content as distinct records.

For instance, a Drupal article on cybersecurity might be linked to its author, relevant taxonomy terms, media files, and related articles. These links allow applications to understand not just the content itself, but how it relates to other information across the website.

Drupal content mapping

Drupal already stores content in a structured way, so it is a good fit for knowledge graphs. Typical entities are:

Nodes
Taxonomy terms
Individuals
Media files
Custom-entities

These entities become nodes in the graph and relationships such as created by, belongs to or references become the edges between them. This provides a richer picture of the content of the website.

Selecting a Graph Database

Drupal can link to graph databases like Neo4j or Amazon Neptune, where these relationships can be stored and queried efficiently.

The typical workflow would be to extract Drupal content, transform it into graph nodes and relationships and synchronize updates through APIs or event-driven processes whenever content is created or modified.

Improving Search and Recommendations

Knowledge graphs greatly enhance the discovery of content by understanding relationships rather than relying just on keywords.

For example, a user looking for Drupal security might also find relevant articles on authentication, access control and secure module development, even if the exact keywords are not used.

Those very same relationships can drive recommendation engines that recommend related content based on the context, not just simple categories or tags.

Combining AI with Knowledge Graphs

Knowledge graphs provide structured context to enhance AI applications. LLMs can leverage graph relations to fetch precise information, reduce irrelevant responses and improve question answering.

This makes Drupal a great base for AI-Powered Chatbots, Enterprise Knowledge Bases, and Intelligent Documentation Systems.

Good Practice

If you are building a Drupal Knowledge graph, you should consider the following:

Sync the graph with your Drupal content.
Use consistent identifiers and metadata.
Use secure graph APIs and restrict access to sensitive data.
Optimize graph query for performance and scale
Check data quality as the graph expands.

These practices will help make the knowledge graph reliable and efficient.

Applications in Real Life

Knowledge graphs can assist many Drupal-powered platforms, including:

Knowledge management systems for enterprise.
Digital libraries, educational portals.
Sites of government and public service.
Documentation and customer support platforms
Information Systems and Research Management.

Conclusion

Once you have a knowledge graph, content is no longer a collection of isolated pages, but instead an interconnected web of information. By capturing relationships between entities, organizations can deliver smarter content recommendations, improve search accuracy and power AI-driven experiences. With the evolution of Semantic Technologies, knowledge graphs provide a scalable and future-ready approach to manage and discover content in Drupal.

Using Vector Databases to Improve Drupal Search

Joshua Wainaina — Sun, 02 Aug 2026 20:27:28 +0000

Introduction

Every content-centric website has the most important search. However, keyword-based searching does not always know the ‘meaning’ behind the search. As Drupal sites become bigger and more complex, users expect the search experience to return relevant results, even when using different words or phrases.

Vector databases solve this problem by enabling semantic search, in which content is represented as AI-generated embeddings that encode context and meaning rather than relying solely on exact keywords. When you have Drupal combined with it, it enhances search efficiency, boosts intelligent recommendations, and offers firm bases for AI applications like chatbots and RAG.

In this article, you will see how the use of vector databases in Drupal will create a faster, smarter, more contextual search experience.

Understanding the Limitations of Traditional Drupal Search

Drupal is a content management framework, which means it organizes content consisting of structured entities such as nodes, taxonomy terms, users, media files, and custom entities. Built-in search module indexes text and inquires the document based on repeated usage of keywords.

This method works fine for many websites, but it still suffers from multiple issues.

Let us say a user searches for something like:

How To Secure Drupal Website?

An example of what your documentation consists of:

Protecting Your Drupal Installation: Best Practices

Since the words “secure” and “protecting” are different, this article will rank poorly with traditional keyword search methods even though they mean nearly the same thing.

Similarly, consider these searches:

Build REST API

Create JSON endpoint

Expose Drupal services

By using human interogation, the topics are almost related, but through keyword-based search, it is considered otherwise unless manual configurations are applied. As websites grow large, the limitations become evident.

Vector Databases

A vector database is designed to hold values generated by AI — embeddings, which are numbers that reflect the meaning of text. It finds the similarity between vectors rather than comparing words.

When a search is sent by a user, everything about the query is turned into an embedding and then compared to vectors that have been stored in order for the top most contextually relevant content to appear.

Popular vector databases include:

Pinecone - A fully managed cloud based services
Weaviate – Open-source, with GraphQL support
Qdrant – High-performance similarity search.
Milvus – Designed for large scale AI applications

Integrating Vector Search with Drupal

Drupal can be connected to vector databases via custom modules or APIs. When content is created or updated, Drupal pulls out the relevant text, generates embeddings with an AI model, and stores them in the vector database along with metadata like the content ID, URL, and taxonomy.

The workflow generally includes the following steps:

Publish or Update Content in Drupal.
Generate an embedding with AI model.
Save the embedding into a vector database.
Convert user search queries to embedding.
Fetch the most semantically similar content.

This process keeps search results in sync with the content on the website and improves relevance.

Hybrid Search for Improved Results

Semantic search helps you understand the context, but if you want to do an exact match, keyword matching is still helpful. A hybrid search system is created that combines both approaches, balancing precision and meaning.

A hybrid search may consider:

Keyword relevance
Semantical similarity
Top Stories
Date of Publication

This gives users the right and relevant search results.

AI Capabilities

After implementing semantic search, Drupal can support advanced AI capabilities such as:

Intelligent Suggestions

Recommend related articles based on meaning, not just common categories or tags.

AI Chatbots

Retrieval-Augmented Generation (RAG) is a method that retrieves Drupal content prior to generating responses, enabling chatbots to produce precise and dependable answers.

Search by Natural Language

Let users ask questions in a conversational way, e.g.

“How do I make my Drupal site more secure?”

The system can return the relevant documentation even if the words do not match the indexed documentation.

Performance and Security

To keep an efficient semantic search system:

Asynchronous embeddings generation.
Update only if the content has changed vectors.
Cache common search queries.
Secure APIs with authentication.
Do not index secret content.
Track search performance and indexing processes

Such practices help ensure scalability, security, and quick response times.

Applications in the real world

Vector databases boost Drupal search in a variety of industries:

Internal documentation for knowledge bases at the enterprise level.
Education platforms that help students find learning resources.
Greater access to public information on government portals.
Healthcare websites with smarter medical guidance retrieval.
Developer docs full of technical questions and programming lingo.

Conclusion

Vector databases are changing Drupal search from a traditional keyword-based system to an intelligent semantic search platform. Organizations can use AI-generated embeddings to provide more relevant search results, improve content discovery, and develop advanced features such as personalized recommendations and AI-powered chatbots. With the advent of semantic search becoming more relevant, the combination of vector databases with Drupal offers a scalable and future-proof solution for managing and discovering digital content.

Wand Library in Python

Joshua Wainaina — Wed, 22 Jul 2026 04:51:20 +0000

Introduction

Wand library in Python contains a module known as ImageMagick. It is an attribute developed to change the format of an image. ImageMagick is extensively used due to its capability to work with image formats in the broader scope and its precision and ease of use. The reason for studying this module in Python is to understand how you can manipulate a single image into various forms.

Therefore, we will take a deep look at the wand Python library, which Imagemagick developed. Furthermore, with the help of several examples, which will well explain, we will learn about the features and applications of the Wand library in the Python programming language.

Prerequisite

For a learner to have a complete understanding of this topic, they should have some knowledge of Python and should also have Python installed in their machine for easier running of code.

Defining Wand library
Installation Verification
How can we read an image in Python Wand?
Use Wand package in Python to blur an image
Image transform using Python wand
Use Python wand to draw an image
How does wand library compare with other libraries?
Conclusion

Defining Wand library

Using Python programming language, which created a library known as Imagemagick, then the wand library was generated from here. Using Wand library, images are manipulated in several ways, discussed later in the article. We can use the Wand to edit and open images, but in collaboration with NumPy, it offers significant functions for machine learning codes. Below are some of its uses.

We can use it to display a single image in several outlooks, e.g., upside down, blurred, etc.
This package additionally enhances the photos with various effects.
Image scaling and cropping are also supported.
The wand library can read and write images in various formats.

We shall now take a look at how to install Wand library.

Let us check the following syntax, and in this case, we will use Ubuntu.

pip install Wand

The python module wand will be installed in the machine as a version of pip and Python.

Again, we must include the ImageMagick dependencies because the wand library is an Imagick API. The reason for having the dependencies is that they contain functions responsible for manipulating images, e.g., drawing.

sudo apt-get install libmagickwand-dev

To learn and have a comprehensive understanding of the ImageMagick dependency installation and the various actions that are performed to it during the installation process, follow this link.

Installation Verification

After successfully installing the wand python module and Imagemagick dependencies in the machine, we will test by importing Wand. Using an editing environment of your choice, create a Python file and save it with a .py extension, e.g., test.py, and then type import wand in the created file. If Wand were successfully installed, it would automatically pop up. Otherwise, Wand was not established.

import wand

How can we read an image in Python Wand?

By implementing the Wand's picture library's Image module, one will import image files. After that, We will use numerous properties such as height, width, and so to interpret the image.

Now let us look at a complete example of checking the width and height of an image by following the above three steps.

from Wand.image import image as wandImage  # We will start importing the image library from the Wand.

with wandImage(filename='/wand-library-in-python/python.png') as img:  # The second step is to import the image using its correct pathname.

     # The third step is to print the image's height and width.
    print('The Height of the image is:', img.height)
    print('The width of the image is:', img.width)

The initial step is importing the image library from the Wand.
The second step in this process is to import an image that you want to get its details.
However, to ensure that the image details will be output successfully, the correct pathname should be input and in the correct format. Furthermore, this mainly applies to an image located within several folders. The following format should be used when encountering such an image.
The third step is now to print the details of the image, i.e., the width and the height.

The input image is:

The output is as follows.

The height of the image is: 203
The width of the image is: 601

Use Wand package in Python to blur an image

We can use several ways in Python to blur an image. For example, one can decide to blur an image using the pillow package, another one can abandon the pillow package and use the OpenCV library, and all will perform the same job. However, in our case, we will use the Wand library to blur the same image, and the following are the steps that we shall use.

Let us take a look at an example.

from Wand.image import Image as wandImage  # Importing the image library from Wand
with wandImage(filename='/wand-library-in-python/python.png') as img:  # Importing the image using the correct image location.

    img.blur(radius=1, sigma=3) # Blur function and its dimensions    

    img.save(filename='/wand-library-in-python/python1.png') # Saving the blurred image using in a certain location.

We shall import the image library from Wand as we had done in our previous example.
We shall then import our image using the correct pathname.
We shall then call the blur function by specifying the radius and sigma of the image. The radius parameter is used to determine the radius of the gaussian aperture, which is the size of the gap, and it is always an integer number, e.g., 3. Gaussian aperture function is to focus on what will be output. The sigma parameter is used to describe the sigma value, and it is also an integer input, e.g., 5.
The last step is to save the image from differentiating it from the original image.

The input image is:

The output image is:

Image transform using Python wand

Another essential and robust feature of the Python wand is the image transform feature. It transforms an image to be displayed differently from the original image, e.g., an image can be changed and be outputted as an upside-down image.

Image transformation, in this case, means that the output of the image will be upsidedown and reversed compared to the input image. The image transformation is achieved through the collaboration of several functions.

Let us consider a complete example.

from Wand.image import Image  # Let us import the image library

with Image(filename='/wand-library-in-python/python1.png') as img:  # Get image


    with image.clone() as flip: # Clone image
        flip.flip() # flip function. The flip function is used to reverse the order of elements.

        flip.save(filename='/wand-library-in-python/python2.png') # Save image

The following steps are used to transform an image.

The first and second steps shall be referred to in the above examples, i.e., importing the image library from Wand and importing the image.
The clone() function is called for making the image.
The cloned image is then saved in a specific location.

The input image is:

The image output is:

Use Python wand to draw an image

Apart from all those features that we have looked at, drawing an image and displaying it is possible. We will achieve this by using a combination of various functions.

Below is an example description:

from wand.image import Image  
from wand.drawing import Drawing  
from wand.color import Color  
with Drawing() as img_draw:  
    img_draw.stroke_color=Color('red')
    img_draw.stroke_width=4

    img_draw.fill_color=Color('white')
    img_draw.circle((300, 300), (200, 200)) 
    with Image(  
        width = 480,  
        height =600,  
        background = Color('blue')  
        ) as img:  
        img_draw(img)  
        img.save(filename = '/wand-library-in-python/python5.png')

The steps to be followed when implementing the above piece of code are as follows:
The initial step in the description example above is to import the required modules, i.e., color, image, and drawing, so that the desired output may be found.

After that, specify the color of the image and the size the image shall cover.
Then, determine the outside border of the image together with its color.
The image is then saved as the final step.

To draw an image using a python Wand, a color is specified(any color can do). The size of what the image will cover is also determined. Then the overall dimensions of the image coverage are also determined.

The output image is :

How does wand library compare with other libraries?

Apart from the wand library that we have discussed, other libraries are also used to manipulate images, i.e., pillow and OpenCV. We are going to look at how these libraries differ from each other.

OpenCV library is developed using C and C++ programming languages, while the pillow is designed using C and python programming languages. However, OpenCV is faster compared to pillow when dealing with image manipulation. In the same manner, OpenCV still becomes superior to wand library, and hence it becomes the best out of all three that can best manipulate images.

However, even if these libraries are developed using different languages, their functionalities are almost identical because the image manipulation techniques across the libraries are practically similar.

For example, let's have a look at resizing an image using pillow package.

from PIL import Image
image=Image.open('python.png')
new_image=image.resize((200,200))
new_image.save('pp.png')
print(image.size)
print(new_image.size)

Output

Original image
(601, 203)

Resized image
(200, 200)

The input image was which was:

The image was initially of size 601 by 203, and after performing a resize, the picture looked as follows.

Output image:

The above example displays some of the functionalities performed by Pillow package.

Conclusion

In conclusion, we had outlined what one can do using the image library in Wand—blurring an image, drawing, and transforming the same idea. This has proved that it can use a single image but have several displays, which is achieved by calling several functions.

For further studies about this topic, click this link.

A look at c# coding conventions

Joshua Wainaina — Wed, 22 Jul 2026 03:29:51 +0000

Introduction

This article outlines a set of coding guidelines, design principles, and naming conventions for the C# programming language and the .NET framework. It lays out the rules in a format that is simple to read and understand, allowing software engineers to apply them rapidly.

The article's aim is to serve as a primary source of information and efficiency for programmers.

Benefits of coding conventions:

They make copying, changing, and maintaining code a lot easier.
They help readers understand the code faster by allowing them to make assumptions based on prior knowledge.
They give the code a unified design so readers may concentrate on the content rather than the layout.
They tell the most ideal manner to use the C# programming language.

Several coding conventions are used in the C# programming language:

Naming conventions
Layout conventions
Commenting conventions

There are a few naming conventions that should be followed while writing C# code. All information about public elements applies as well to protected and protected internal elements in the following scenarios, which are all supposed to be visible to external callers.

Naming conventions

Pascal's case

In the Pascal case, the first letter of every word is capitalized as displayed in the example below. One can use the Pascal case for identifiers with three or more characters.

When naming a class, record, or struct, use pascal casing ("PascalCasing").

PublicSchool1

public class PascalCase1
{
}
public record PublicIntitution1(
    string Country,
    string County,
    string Village,
    );
public struct ValueCoordinate1
{
}

Besides to prefixing the name with an I, when naming an interface, use the pascal casing. Customers can tell it's a user interface because of this.

public interface IPublicInstitution
{
}

Besides to what is already there, public members of types can be named using the pascal case.

public class PracticeExample1
{
    // public field
    public bool IsValid;

    // An init-only property is a property that allows you to do something only once.
    public IBuilding Building { get; init; }

    // An example of an event
    public event Action EventProcessing;

    // Implementation of a method
    public void StartEventProcessing()
    {
        // Use of a local function
        static int CountQueueItems() => WorkerQueue.Count;

    }
}

Since parameters are public properties of the record, a reader can use pascal casing when putting down positional accounts.

public record PublicIntitution
(
    string Country,
    string County,
    string Village,
);

Camel case

The camelCasing convention, which is used for parameter names, capitalizes the first letter of each word except the first.

voidMain

Another implementation of the camel case is when naming private or internal fields.

public class DataService
{
    private IWorkerQueue _workerQueue;
}

It is also advisable to use the s_prefix and the t_prefix for the static fields respectively when dealing with thread and internal fields.

public class DataService
{
    private static IWorkerQueue s_workerQueue;

    [ThreadStatic]
    private static TimeSpan t_timeSpan;
}

Camel casing is used when executing most of the method parameters.

public T SomeMethod<T>(int someNumber, bool isValid)
{
}

Apart from the above conventions, there are other several conventions that a programmer needs to consider and apply while in their daily routine of programming.

The choice of word - Use readable identifier names. Underscores, hyphens, and other non-alphanumeric characters should not be used. The choice of word implies that not any word can be used when programming, instead the proper words should be used.
Hungarian notation is neither acceptable nor encouraged - A hungarian notation is whereby the name of a variable or function denotes its intent or kind, as well as its type in some languages. This therefore creates a programming language dependency and makes maintenance more difficult.
The use of abbreviations and acronyms - Do not use acronyms that aren't generally recognized, and even if they are, only use them when essential.
Abbreviations and contractions should not be used as identifier names - This simply means that when one is writing an identifier, words should not be contracted but instead well-known identifiers should be used.

Layout Conventions

For a clear understanding of the code and its structure, formatting is exercised as a coding convention.

Some of the layout coding conventions are:

Use the code editor's default settings that use smart indenting, four-character indents, and tabs that are saved as spaces.
Each line should accommodate one statement. i.e // This is a comment for a single statement. The disqualified one is, // This is a comment 1, This is another comment. Each single comment should be in a sigle statement.
Each line should only accommodate one declaration. eg varx=13; and not var x=13; var y =14;
If the continuation lines are not indented consequently, they are supposed to be indented at a stop of one tab.
At least a single blank line is supposed to be added between the property definitions and the method. It is done to make sure that your code is clean and neat so that it is readable. A reader will have an easy time following your code and know what each line entails.

Use enclosure or parenthesis to make provisions in an articulation clear, as displayed in the code below.

if ((valxyz > valxyz) && (valabc > valabc))
{
    // Here is what you will do.
}

Coding conventions for commenting

It is advisable to write a comment on its separate line for understandability.
It is also wise to start a comment with an uppercase letter.
The remark content should be ended with a period.
It is also advisable to place a single space between the comment delimiter // and the comment content, as displayed in the example below.

// This is a comment used in the C-Sharp programming language.
// This is a single-line comment.

It is not advisable to use formatted blocks of asterisks * to surround comments.
Unearth that all public members are using the appropriate XML comments to describe their actions.

A look at some language guidelines

String data types

To join small strings end to end, string interpolation is used as explained in the example below.

string displayDetails2 = $"{detailsList2[n].FullName}, {detailsList2[n].JobId}";

When working with a huge volume of text, one can use a StringBuilder object to attach strings in loops.

var phrase = "programmmmmmmmmmmmming";
var manyPhrases = new StringBuilder();
for (var j = 0; j < 1000; j++)
{
    manyPhrases.Append(phrase);
}

Event handlers with relaxed delegates

Event handler arguments (Object and EventArgs) should not be qualified explicitly, use relaxed delegates instead of event arguments if you're not utilizing the event parameters.

Take the following as an example:

(sender as Object, e As EventArgs)

The unsigned data type

Use int instead of unsigned types in general. In C#, int is widely used, making communication with other libraries easy.

Arrays

When initializing arrays on the declaration line, use the succinct syntax. Let's use string[] in the following example.

string[] alphabets1 = { "u", "v", "w", "x", "y", "z" };
You can use var if you utilize explicit instantiation.
var aplphabets2 = new string[] { "u", "v", "w", "x", "y", "z" };

If you specify an array size, then the elements should be initialized one by one.

var alphabet3 = new string[5];
alphabet3[0] = "a";
alphabet3[1] = "b";
// And the process continues.

Conclusion

In conclusion, a code is not only written but written under strict rules or standards that enables the output to be much more correct and to perform its task.

The following is achieved using the coding conventions:

Users will put their focus on the content rather than the layout because your code will have a consistent appearance.
Based on earlier experience, readers may understand your code easily.
Code becomes easier to copy, update, and maintain.
You contribute to ensuring that your code follows Visual Basic's "best practices".

Follow the conventions to become a perfect programmer!

Use geopy to calculate the distance between two points

Joshua Wainaina — Tue, 23 Jun 2026 12:19:24 +0000

The Geopy method for distance calculation between any two points on the globe.

Introduction.

Geopy is essentially a Python library that makes the calculation of geographic distances unchalleging. It becomes considerably easier for developers using Geopy to retrieve the coordinates of various sites by leveraging third-party geocoders and other data sources.

In this article, we'll look at a few alternative ways for calculating the distance between any two points on the globe. We shall dig deep to explain how this is possible using Python package geopy which is the primary Python package for distance calculation.

The user needs first to execute the following command to install geopy.

Before executing the command below, there is a series of steps that are followed so that the command is finally arrived at.

Open your cmd and make sure it is running as an administrator.
Make sure that you are operating from the root by performing the following. cd..
cd.. This shows that you are already at the root.
After that now you can perform the command below and geopy will be installed in your machine.

pip install geopy

We are therefore set to calculate the distances of any two points following a successful installation of the geopy module.

Using the Geopy, we can calculate or find the distance between two strategic positions using the various methods that are listed below.

Distance Measure using the Geodesic Measure.
Distance Measure using The greate circle distance.
Distance Measure using The Herversine formula. ### The Geodesic Measure for distance calculation. The geodesic measure or distance is used to define the shortest path between any two given points on the globe.

As in the situation of two diametrically opposing points on a sphere, it is feasible that numerous alternative arcs between two points reduce the distance. In this case, any of these curves is a geodesic. Geodesics are not exactly the same as " the shortest curves" between any two given locations, despite their likeness.

It is rather defined in a better way as the shortest distance between two points at a given position that is parameterized with "constant speed." A geodesic is the "long way around" on a great circle between two points on an earth's surface, even if it is not the shortest path between the two points.

An important point to note when working with geodesic or when calculating any distance between any two points on the sphere is that it does not ignore any curved part. In contrast to this, a distance calculation known as Euclidean distance completely ignores the shape of the path that is involved such that it assumes a straight path from the start of a point to its end.

We'll illustrate how to compute or how to calculate the Geodesic Distance using latitude and longitude data in the following example.

Example 1.1

# To begin, open the geopy library and import the geodesic module. 
from geopy.distance import geodesic as GD
 # Then, for the specified locations, load their latitude and longitude data.
Abuja =(9.072264 , 7.491302)
Dakar =(14.716677 , -17.467686)
#Finally, print the distance between two sites in kilometers.
print("The distance between Abuja  and Dakar is:", GD(Abuja, Dakar).km)

See terminal output below:

The distance between Abuja  and Dakar is: 2787.8012928541466

Example 1.2

# Geopy distance module is first imported for the purpose of computations.

from geopy.distance import geodesic as GD
# Next, input the latitude and longitude data for Nairobi and Cairo.  

Nairobi=(36.817223,-1.286389 )
Cairo=( 31.233334,30.033333, )
# Finally, print the distance between two sites in kilometers. 

print("The distance between Nairobi and Cairo is :",GD(Nairobi,Cairo).km)

See terminal output below:

The distance between Nairobi and Cairo is : 2944.261368793268

The outputs from the two examples above are obtained by loading the latitude data first then the longitude data. If we try to exchange the order in which the two are loaded i.e we load the longitude data first then the latitude data last, the distance obtained will not be equal with the original distance. Let us have a proof on that by using the data in example 1.1 above.

# To begin, open the geopy library and import the geodesic module. 
from geopy.distance import geodesic as GD
# Then, for the specified locations, load their longitude and latitude data
Abuja=(7.491302, 9.072264 )
Dakar=(-17.467686, 14.716677)
#Finally, print the distance between two sites in kilometers.
print("The distance between Abuja and Dakar is:", GD(
Abuja, Dakar).km)

See terminal output below:

The distance between Abuja and Dakar is: 2829.4255581410116

The comparison is as follows:

The distance between Abuja  and Dakar is(Latitude data first followed by longitude data): 2787.8012928541466

The distance between Abuja and Dakar is (Longitude data first followed by the latitude data): 2829.4255581410116

It is very clear that the two distances are not the same. And this will apply to all other methods and it is, therefore, a good practice to begin with the latitude data followed by the longitude data

The great circle distance formula for distance calculation.

This may be defined as the shortest path between any two places or points on the sphere or on the earth's surface. In this example, it is assumed that the globe is a perfect sphere. The following example shows how to compute great circle distance using longitude and latitude data from two locations.

The problem of great-circle navigation includes the computation of azimuths at end points and intermediate waypoints, as well as the calculation of the great-circle distance.

A great circle is formed by any two points on a sphere that are not directly opposite with each other. The great circle is divided into two arcs by these two locations. The shorter arc that is between any two locations equals to the great-circle distance.

Example 1.3

 # First, import the geopy library's great circle module.
from geopy.distance import great_circle as GRC
# Abuja and Dakar latitude and longitude data.
Abuja=(9.072264 , 7.491302)
Dakar=(14.716677 , -17.467686)
# ## Finally print the distance between the two points calculated in km
print("The distance between Abuja  and Dakar is:", GRC(Abuja,Dakar).km)

See terminal output below:

The distance between Abuja  and Dakar is: 2785.186971064666

The Heversine formula for distance calculation.

The heversine formula executes the great-circle distance between any two points on a sphere using their longitudes and latitudes.

One specific example is the rule of haversines, a more general formula in the field of spherical trigonometry that connects the sides and angles of spherical triangles.

The haversine method therefore gives a very correct way of finding the distance between any two given longitude and latitude.

The haversine formula is a realignment of the spherical law of cosines, although it is more useful for tiny angles and distances since it is written in haversines.

The "Ha" in "Haversine" represents "half versed sine," and haversin(θ) = versin(θ)/2 is the formula.
The orthodromic distance is used to calculate the shortest distance between two sites on the globe separated by latitude and longitude.

If the user want to utilize this method, then they must have the coordinates of two points (X and Y).
They must convert degrees of latitude and longitude to radians before dividing the data by (180/π) and the value of π to be used is 22/7.

"57.29577" will be the value of (180/π).

The user may wish to find the distance in miles where the radius of the Earth can be set to "3,963." The user can also use the value "6,378.80" to compute the distance in Kilometres.

Formulas

Longitude in radians is calculated as follows: In radians, the value of latitude is: Latitude (LaA) = LaA / (180/π )

Latitude (LaA) = LaA / 57.29577
How to compute longitude in radians:
Longitude (LoA) = LoA / (180/π )

Longitude (LoA) = LoA / 57.29577

The longitude and latitude coordinates of P and Q locations, as well as the aforementioned method to convert them to radians, will be required by the user.

By utilizing the following method, distance between any two points can be found.

Hundreds of miles

Distance (D) = 3963.0 * arccos[(sin(LaA) * sin(LaB)) + cos(LaA) * cos(LaB) * cos(LoB - LoA)]

For the kilometer

Distance (D) = 3963.0 * arccos[(sin(LaA) * sin(LaB)) + cos(LaA) * cos(LaB) * cos(LoB - LoA)]

For the kilometer: The shortest distance between two specified points on Earth can be calculated using the Haversine Formula.

Example 1.4

from math import radians, cos, sin, asin, sqrt

# Implement the formula below

def distance_d(LaA, LaB, LoA, LoB):
# The function "radians" is found in the math module, It's also used to convert radians to degrees.  
LoA = radians(LoA)  
LoB = radians(LoB)  
LaA= radians(LaA)  
LaB = radians(LaB) 
# The "Haversine formula" is used.
D_Lo = LoB - LoA 
D_La = LaB - LaA 
P = sin(D_La / 2)**2 + cos(LaA) * cos(LaB) * sin(D_Lo / 2)**2  

Q = 2 * asin(sqrt(P))   
    # The earth's radius in kilometers.
R_km = 6371  
# Then we'll compute the outcome.
return(Q * R km).


LaA=9.072264
LaB=14.716677
LoA=7.491302
LoB=-17.467686

print ("The distance between Abuja and Dakar is: ", distance_d(LaA, LaB, LoA, LoB), "K.M")

See terminal output below:

The distance between Abuja and Dakar is:  2785.183036572855 K.M

Conclusion

Using the geopy package, we've gone over numerous ways for determining the distance between two points on the earth's surface in this tutorial. Each approach has been demonstrated using examples.
Happy Coding

Adding custom methods for linq queries

Joshua Wainaina — Tue, 23 Jun 2026 12:15:36 +0000

Adding custom methods for LINQ queries (C#)

Introduction

By introducing extension methods to the IEnumerableT> interface, you may expand the set of methods available for LINQ queries. Any data sequence can be converted into one single value by creating your custom aggregate method in SQL Server.

You can also build a method that returns a new series of values and acts as a custom filter or a specialized data transform for a sequence of variables.

A few examples include the Distinct and Skip techniques, as well as the Reverse.

You may apply your methods to any enumerable collection when you extend the IEnumerableT> interface. In this article, we shall deeply take a look at various custom methods that are used in LINQ queries in C#.

Adding an aggregate method

When a set of values is aggregated, a single value can be generated. Average, Min, and Max are just a few of the aggregate techniques available in LINQ. By introducing an extension method to the IEnumerableT> interface, you can design your aggregate method.

Median is an extension method that computes the median of a sequence of double-valued numbers.

public static class LINQExtensionExample
{
    public static double Median(this IEnumerable<double>? source)
    {
        if (!(source?.Any() ?? false))
        {
            throw a new InvalidOperationException("A null or empty set cannot be used to compute the median..");
        }

        var sortedList = (from numberX in source
                          orderby numberX
                          select numberX).ToList();

        int itemIndex = sortedList.Count / 2;

        if (sortedList.Count % 2 == 0)
        {
            // Rerurning an even number of objects or items
            return (sortedList[itemIndex] + sortedList[itemIndex - 1]) / 2;
        }
        else
        {
            // Rerurning an odd number of objects or items
            return sortedList[itemIndex];
        }
    }
}

There is no difference between calling this extension method from the IEnumerableT> interface and calling any other aggregate function.

On a double array, the following code demonstrates using the Median method

double[] numbers1 = { 0.9, 5, 2, 9.3, 2.6, 7, 3.3, 4 };

var query = numbers1.Median();

Console.WriteLine("double: Median = " + query1);
/*
 The output of the above code is as shown below

 Double: Median = 5.95
*/

An aggregate method is overloaded by accepting a variety of types.

To accept sequences of different types, you can overload your aggregate method. Overloading each type is the typical technique. It's also possible to use a delegate to build an overload for a generic type. Combining both approaches is also an option.

To build a type overload

A separate overload for each kind you want to support can be created. Here's an int-type overload of the Median method, which you can see in the following code example.

//Overload of int
public static double Median(this IEnumerable<int> source) =>
    (from numX in source select (double)numX).Median();
With the new Median overloads available for both integer and double types, the following code shows how to use them:
double[] numbers2 = {  0.9, 5, 2, 9.3, 2.6, 7, 3.3, 4};

var query2 = numbers2.Median();

Console.WriteLine("double: Median = " + query2);

int[] numbers3 = { 14, 16, 15, 13, 11, 10, 9 };

var query3 = numbers3.Median();

Console.WriteLine("int: Median = " + query3);
/*
 Here's what it looks like when it runs:

 The Double part: Median = 5.95
 The Integer part: Median = 13
*/

Initiating a generic overflow

A list of generic objects can also be used as an input to an overload if you want to do that. Delegate is supplied as a variable in this overload which converts the generic objects into a specific type using the delegate.

An overload of Median's FuncT,TResult> delegate is shown in the following code. An object of generic type T is passed to this delegate, and it returns a double-type object as a result.

// Let us take a look
public static double Median<T>(this IEnumerable<T> numbersY,
                       Func<T, double> selector) =>
    (from num in numbersY select selector(num)).Median();

When working with sequences of objects of any type, you may now use the Median technique. A delegate parameter must be passed in if the type does not have its overload of the procedure. Lambda expressions are available in C# for this purpose. When using Aggregate or Group By clauses instead of a method call, this is only true in Visual Basic.

You can use the following code to call the Median method on a string array as well as an integer array. Using an array of strings, a median is derived for each string's lengths in the array. Use the Median method's delegate parameter for each scenario in the code. Use the Median method's delegate parameter for FuncT, TResult> for each scenario in which it's used.

int[] numbers4 = { 14, 16, 15, 13, 11, 10, 9 };

/*
   In this case, the compiler will implicitly convert num=>num's value to double when you pass it as a parameter to the Median method.
   Otherwise, the compiler will give the user an error message.
*/
var query4 = numbers4.Median(num => num);

Console.WriteLine("int: Median = " + query3);

string[] numbers5 = { "fourteen", "sixteen", "fifteen", "thirteen", "eleven", "ten", "nine" };

// A number of object properties are available with the generic overload.

var query5 = numbers5.Median(str => str.Length);

Console.WriteLine("String: Median = " + query5);

/*
Here's what it looks like when it runs:
 Integer: Median = 13
 String: Median = 13
*/

Adding a method that returns a sequence

IENumerableT can be extended with custom query methods to return a sequence of values. A collection of IEnumerableT> must be returned in this scenario. Filters or data transformations can be applied to a sequence of values using these methods.

Using the AlternateElements Extension Method, every other element in a collection, starting with the first element, is returned.

//The IEnumerableT> interface has an extension method.
// Every other element in a sequence is returned by the method.
public static IEnumerable<T> AlternateElements<T>(this IEnumerable<T> source)
{
    int y = 3;
    foreach (var element in source)
    {
        if (y % 2 == 1)
        {
            yield return element;
        }
        y++;
    }
}

This function can be used to extend any enumerable collection.

string[] strings = { "u", "v", "w", "x" };

var query4 = strings.AlternateElements();

foreach (var element in query6)
{
    Console.WriteLine(element);
}
/*
Here's what it looks like when it runs:
 u
 w

*/

Conclusion

In conclusion, we have looked at how one as a programmer can add custom methods for LINQ queries in c#.

Key differences between python and javascript

Joshua Wainaina — Tue, 23 Jun 2026 11:53:18 +0000

Key differences between python and JavaScript

Introduction

Python and JavaScript are important languages that are used in web development. Python is a language that can be used in the backend development of a web application. JavaScript on the other hand is a language that can be used in both the frontend and backend development of a web application.

However, despite the difference in development part that each language plays, the two languages have other big differences that we are going to look into detail in this article.

Real World application of Python and JavaScript.

Python is mostly used in scientific and specialized applications as it is also used in web development.

JavaScript is widely used in web development.

Syntax, Sentactical and Functional differences between Python and JavaScript

Python and Js have different Syntax.
Python and JavaScript have some key differences in terms of the syntax used in performing various activities.

Code blocks in python and JavaScript

In Python, when several lines of code are indented, then they are said to be of the same code block.

Example

if  t  > 10:

     print (t)

In JavaScript, notwithstanding, wavy supports are utilized rather than space to bunch explanations that have a place with a similar code block.

Let's look at an example.

if (t>10)

{

    console.log(t)

}

Definition of variables

When defining a variable in python, a variable name is written followed by an equal (=) sign. Then a value is assigned to the variable. i.e

<variable_name > = value

x = 56

In JavaScript, a keyword var is added before the variable name and a semicolon is used to terminate the statement i.e

var <variable_name>  = value;

eg  var k=34;

Variable Naming Conventions

In Python, the snake_case naming style is used. The names should be in lowercase and separated by an underscore as shown below.

first_name

In JavaScript, lowerCamelCase is used. The variable name starts with a lowercase letter and every other new word starts with an uppercase letter.

myFirstName

Constants in Python and JavaScript.

Constants

In Python, constants are written in uppercase format separated by an underscore. ie. CONSTANT_NAME.

For example:

PASS_RATE = 4

In JavaScript, a keyword const is added before the constant name and a semicolon is used to terminate the statement. ie. const CONSTANT_NAME = value;

const AGE=56;

Data types and values in Python and JavaScript

1) Numeric data types

In python, we have three numeric sorts that will assist us with accomplishing exact estimations for logical purposes. These are :

In JavaScript, we have two numeric types i.e Numbersand BigInt. The two whole numbers and coasting point numbers are viewed as type numbers.

None and null in python and JavaScript

In python, when a variable doesn't have a worth at a specific point in the program, it is alloted an extraordinary worth called None.

In JavaScript, the same worth is null which addresses the shortfall of any item esteem.

The undefined value

In python, one needs to allocate an underlying worth to the variable. One cannot declare a variable without an initial value.

In Javascript, we have a unique worth that is allocated consequently. When a variable is declared without assigning an initial value, it prints out undefined as shown below;

var k; // should print undefined

Primitive data types

Python have four primitive data types:

Intergers.
float.
boolean (https://www.codesansar.com/python-programming/fundamental-or-primitive-data-types.htm#bool).
strings.

On the other hand, JavaScript have six primitative data types:

Comments

Commenting is done for any reason. For example, one may comment on a line for future reference.

1. Single-line comments

Comment spanning a single line. Look at the example below:
In python, a hashtag (#) is used to comment on a single line.

# this is a  single-line comment in python

As shown above we have used a hashtag(#) to comment on a single line in Python.

In JavaScript double slashes (//) are used to comment on a single line.

//this is a single-line comment in JavaScript

As shown above we have used double slashes (//) to comment on a single line in JavaScript.

2. Multiple line comments

These are comments spanning many lines.

When writing multiple comments in python, we start every single line with a hashtag (#) as shown below:

# this is a   
# multiple lines 
# comment
# as used in Python`

When writing multiple line comments in JavaScript, we use symbols (/*) to open and (*/) to close a comment as shown below:

/*
 This is  a multi-line comment
that span many lines
*/

Built in data structures

1. Tuples

Tuples in Python are similar to lists but immutable.
They are utilized to store information that ought not be changed

In JavaScript, we don't have an inherent construction with such qualities.

2. List and Arrays-->

Records are utilized in python to store a progression of qualities in a similar information structure

number = [3, 4,5]

An array is the equivalent version of this in JavaScript.

var number = [3,4,5]

Comparing values and types

In Python the double equal (==) operator are used to compare if two values and their data types are equal -->

11 == 11 #True
11 == 10 #False

javascript
As shown above, 11 == 11 is true, while11 != 10 is false.

In JavaScript, a triple equivalent ('===') administrator is utilized to look at if two qualities and their information types are equivalent.

5===5  //true
5==='5'  //false

Logical Operators

In python, there are three logical operators:

In JavaScript, the logical operators are also three:

&& -- logical and.
|| -- logical or.
! --logical not. ### Type Operators To check the type of object in python we use the (type()) function as shown below:

type(instance)

To check the type of object in JavaScript we use type of operator as below:

type of instance

Inputs and Outputs

Input is a function that is used to ask the user of the program a question whereby the user have to type the result of the asked question.

Output on the other hand is used to print the specific message that the user inputs.

Inputs

In python input() function is used to ask for user input.

Example

name = input (" Enter your name : ")

In JavaScript, (if you are running your code on console ) it will display a small prompt with window. prompt (message) and assign the result to a variable.

var input =window.prompt ("enter a Number :")

Outputs

In python we print a worth in the comfort with the print() work parsing the qualities inside the enclosure.

Example

num1 = input ("Enter the first  number : ")
num2 = input ("Enter a second  number : ")
num3 = input ("Enter a third number : ")
result= num1 + num2 + num3
print(result)

In JavaScript, we print a value in the console with the print() function parsing the values within the parenthesis.

Example

console.log("My name is John:");

Conditional statements

Conditional statements are used to act if a certain condition is true.

1. if statement

In python, indentation is relied upon to indicate the lines of code that belong to a conditional statement.

if condition:

     code

Let's look at an example:

age = 10
if age < 18:
    print('kid you are!')

In JavaScript, the condition is enclosed in parenthesis and the code enclosed within curly braces which should also be indented as shown in the syntax below:

if (condition)

    {
        code
    }

An example of a snippet would look like:

if (hour > 4) {
  task = "Clean the compound";
}

if else statement

In python, a colon (:) is written after the else keyword.

if condition:

    if code

else :

    else code

Let's look at an example:

age = 34
if age < 18:
    print('kid you are!')
else:
    print('You are not a kid')

In JavaScript, the code that belongs to the elseclause is enclosed in curly braces.

if (condition)

    {
        if code
    }

else 

    {
        else code
    }

Let's look at an example.

var time = new Date().getHours();
if (time < 5) {
  task = "Cleaning the house";
} else {
  task = "Feeding the sheep";
}

Multiple conditions

In python elif keyword is used when dealing with multiple conditions. After every condition we write a semicolon(:) and the code that belongs to the condition is indented in the next line.


if condition1:

    code

elif condition2:

    code

elif condition3:

    code

else:

    code

Let's look at an example.

age = 40
if age < 18:
    print('kid you are!')
elif age >=18 and age < 29:
    print('You are a youngst!')
elif age >=29 and age < 35:
    print('You are middle aged!')
else:
    print('You are above middle age !')

In JavaScript else if keyword is used when dealing with multiple conditions. The conditions are surrounded by parenthesis.

if(condition1)

    {
        //code
    }

else if(condition2)

    {
       // code
    }

else if (condition3)

    {
        //code
    }

else

    {
        //code
    }

Let's look at an example.

var time = new Date().getHours();
if (time < 5) {
  task = "Cleaning the house";
} else if (time < 15) {
  task = "Feeding the sheep";
} else {
  task = "Watching a movie";
}

Switch

Python does not have this type of built-in control structure i.e switch

In JavaScript, a switch is utilized to pick what happens depends on the worth of an articulation.

switch(expression)

    {
        case 1:
        code
        break;

        case 2:
        code
        break;

        case 3:
        code
        break;

        default:
        code
    }

Let's look at an example.

switch (new Month().getMonth()) {
  case 1:
    month = "January";
    break;
  case 2:
    day = "April";
    break;
  case 3:
     day = "May";
    break;
  case 4:
    day = "June";
    break;
  case 5:
    day = "August";
    break;
  case 6:
    day = "September";
    break;
  default:
  No such a month;
}

Loops

A loop is a control structure that repeats a series of instructions until a specified condition is reached.

For Loops

We write a for loop in Python as shown below.

for x in range(k):

    code

The syntax of writing a for loop in JavaScript is as follows.

for(var x = 1; x >n ; x++)

{

        code
}

While Loop

It is a pre-test loop in which the condition is evaluated before the loop executes.

In Python, we compose the watchword while trailed by the condition, and afterward, a colon (:), and afterward the body of the circle in another line in an indented mode.


while condition: code

In JavaScript, the linguistic structure is the same. The distinctions are that we need to encompass the condition with enclosures and the body of the circle with wavy supports.

while(condition)

{

    code

}

Do while loops

This is a post-test loop. The condition is evaluated after the loop executes

In python, we do not have such a control structure (do-while loop)

In JavaScript, this loop will always be executed
once.


do { code } while (condition);

Functions

A Function is a block of code that plays out a specific undertaking. In Python, we utilize a watchword def which is trailed by the name of the function. Then the parameters are enclosed in parenthesis and then a full colon immediately after the parameters are enclosed in parenthesis, after which an indented code is written.

 def function_name ( x1 , x2 , x3 , ...):
      code

In JavaScript, the lone contrasts are that we characterize a capacity utilizing the 'work catchphrase 'and encompass the body of the capacity with 'wavy supports'.

function function_name (x1,x2,x3,...)

{

    code
}

Object Oriented Programming(OOP)

OOP is the development of programs in terms of objects that interacts with each other.

Both Python and JavaScript do uphold Object-Oriented programming.

The syntax of defining a class in both Python and JavaScript is almost the same there is a slight difference.

In python a colon is written after the keyword class whereas curlybraces are used in Javascript.

Python

class Rectangle:

    code

JavaScript

class Rectangle

{

    code
}

Constructor and Attributes

A constructor is a member function of a class that executes automatically whenever an object is created.

In Python, a constructor that instates the new example is known as init with two driving and following highlights. This strategy is called consequently when an example of the class is made to introduce it's ascribes. Its boundaries list characterizes the qualities that we need to pass to make the example. This rundown begins with self as the principal boundary.

 class Rectangle:

        def _init _(self , length , width):
            self.length= length
            self.width=width

In JavaScript, a constructor strategy is called constructor and it has a rundown of boundaries as python has.

class Rectangle

{

    constructor(length,width){
        this.length=length;
        this.width=width;

    }
}

NB

In python, we use self to refer to an instance of a class.
i.e


self.attribute= esteem

While in JavaScript we use this to allude to an occurrence of a class.
i.e


this.attribute=value;

Methods In Python and JavaScript.

We characterize strategies with the 'def watchword' trailed by the name of the technique and the boundaries list inside brackets. This boundaries list begins with the self boundary to allude to the occurrence that is calling the technique. After this rundown, we compose a colon (:) and afterward on another line the body of the technique indented.

 class Rectangle:

        def _init _(self , length , width):
            self.length= length
            self.width=width

        def calc_area(self):
             return self.length*width

In javascript the syntax is as shown below.

class Rectangle

{

    constructor(length,width)
    {
        this.length=length;
        this.width=width;
    }

    calcArea()
    {
        return this.length*width;


    }

}

Learning curve

Although these two languages, Python and Javascript, are have got the differences listed above but
In terms of learning and implementing, Python is much easier than JavaScript because its syntax is much easier to understand and also implementing.

DEV Community: Joshua Wainaina

Creating a Knowledge Graph with Drupal Content

Introduction

Knowledge Graphs Explained

Drupal content mapping

Selecting a Graph Database

Improving Search and Recommendations

Combining AI with Knowledge Graphs

Good Practice

Applications in Real Life

Conclusion

Using Vector Databases to Improve Drupal Search

Introduction

Understanding the Limitations of Traditional Drupal Search

Vector Databases

Integrating Vector Search with Drupal

Hybrid Search for Improved Results

AI Capabilities

Intelligent Suggestions

AI Chatbots

Search by Natural Language

Performance and Security

Applications in the real world

Conclusion

Wand Library in Python

Introduction

Prerequisite

Table of contents

Defining Wand library

Installation Verification

How can we read an image in Python Wand?

Use Wand package in Python to blur an image

Image transform using Python wand

Use Python wand to draw an image

How does wand library compare with other libraries?

Conclusion

A look at c# coding conventions

Introduction

Naming conventions

Pascal's case

Camel case

Layout Conventions

Coding conventions for commenting

A look at some language guidelines

String data types

Event handlers with relaxed delegates

The unsigned data type

Arrays

Conclusion

Use geopy to calculate the distance between two points

The Geopy method for distance calculation between any two points on the globe.

Introduction.

The great circle distance formula for distance calculation.

The Heversine formula for distance calculation.

Formulas

Hundreds of miles

For the kilometer

Conclusion

Adding custom methods for linq queries

Adding custom methods for LINQ queries (C#)

Introduction

Adding an aggregate method

An aggregate method is overloaded by accepting a variety of types.

To build a type overload

Initiating a generic overflow

Adding a method that returns a sequence

Conclusion

Key differences between python and javascript

Key differences between python and JavaScript

Introduction

Real World application of Python and JavaScript.

Syntax, Sentactical and Functional differences between Python and JavaScript

Code blocks in python and JavaScript

Example

Definition of variables

Variable Naming Conventions

Constants in Python and JavaScript.

Constants

Data types and values in Python and JavaScript

None and null in python and JavaScript