String Transformation

Python provides methods to modify strings. Remember: strings are immutable, so these methods return new strings rather than modifying the original. strip(), lstrip(), rstrip() The stripped string is "hello world" with length 11. The original had length 17 including the spaces. You can specify which characters to strip: This removes dollar signs from both ends, giving "99.99". The replace() Method You can limit the number of replacements: This replaces only the first 2 occurrences, giving "1 two 1 two one". Removing Characters To remove characters, replace them with an empty string:

About This Interactive Section

This section is part of the Strings: 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.