Searching in Lists

Concepts covered: pyListSearch

Beyond checking if an item exists with the "in" operator (covered in the beginner lesson), Python provides methods to find where items are located and how many times they appear. These are essential for data analysis and processing. The index() Method Search from Any Position By starting the search at different positions, we can find each successive occurrence of the value 10. This is useful when you need to process all occurrences of a value. Handling Not Found Errors The count() Method Finding All Indices Knowing which method to reach for in different situations is key to writing clean, efficient list code. Here is a quick reference for the patterns covered in this lesson. Efficient list manipulation is at the heart of most data processing tasks. Put these techniques to the test with han

About This Interactive Section

This section is part of the Lists: Intermediate lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

How DataDriven Lessons Work

DataDriven combines four interview rounds (SQL, Python, Data Modeling, Pipeline Architecture) with adaptive difficulty and spaced repetition. Easy problems get harder as you improve. Weak concepts resurface until you master them. Your readiness score tracks progress across every topic interviewers test. Every lesson section ends with problems you solve by writing and running real code, not by picking multiple-choice answers.