Summary  
This chapter demonstrates how to manually group items in a collection by iterating through the data, building a mapping from each group key to a list of items, and appending each entry to its appropriate group without relying on built-in grouping helpers.

General domain of usage  
Data processing

Master the art of iteration in PHP! This course takes you from the basics of for, while, and foreach loops to advanced data processing and real-world challenges. Learn to count, filter, accumulate, and transform data with confidence, and discover how to write efficient, readable, and powerful loop-based code.

Explore the core PHP loop constructs and learn how to use them for counting, filtering, accumulation, and more. Build a strong foundation for all your future PHP projects.

Master the foreach loop by working with associative arrays, transforming data, and iterating over real-world datasets.

Learn to use loops for generating reports, tables, and summaries, and discover grouping and aggregation techniques without built-in helpers.

Grouping Data Without Built-in Helpers