This article shows how you can filter child products associated with a configurable product by the child product’s attribute value.
Suppose, we have a configurable product with two attributes (‘size‘ and ‘color‘) and we want to select only those child products with certain size and/or certain color. Let’s say, we want to select only those products that have color as ‘Red‘.

This article shows how we can check if a module is installed / enabled or active in Magento 2.
Both Dependency Injection and Object Manager ways are shown below.
Using Dependency Injection (DI)

In Magento 1.x, you could call/print any module’s template block in any other template (phtml) file with the following code:

In Magento 1.x, you could call/print the CMS Static Block in template file with the following code:

To display/show product price including tax amount, you need to do some configuration settings.
1. Create Tax Rule
You need to create tax rules (Sales -> Tax -> Manage Tax Rules). For this, you can refer to different tutorials available over the internet on creating Tax rules.

Apache Mahout is a project of Apache Software Foundation. Mahout helps building scalable Machine Learning applications. It primarily focuses in the areas of Collaborative Filtering, Classification, and Clustering.
Here is a very nice video tutorial on Mahout Item Recommender Tutorial using Java and Eclipse. It thoroughly explains about how to use Movielens dataset and create an Item-based recommender system to recommend certain number of most similar items for each items.

This article shows how to use AJAX on Magento with Prototype Javascript Library.
Scenario
I had one scenario where I had to check whether a customer is already registered or not via AJAX.

Crab as known as scikits.recommender is a Python framework for building recommender engines integrated with the world of scientific Python packages (numpy, scipy, matplotlib).
Currently, Crab supports two Recommender Algorithms: User-based Collaborative Filtering and Item-based Collaborative Filtering.

This article shows how we can get parent category, children categories and total number of products in a category in Magento 2.
Below is a block class of my custom module (Chapagain_HelloWorld). I have injected object of \Magento\Catalog\Model\CategoryFactory class in the constructor of my module’s block class.

This article shows how we can get all products of a particular category in Magento 2.
Both Dependency Injection and Object Manager way of coding is shown below.
Using Dependency Injection (DI)