List Patterns
Learn essential list patterns: building lists, flattening, chunking, searching, and removing items safely, using clean beginner-friendly techniques.
This lesson teaches list patterns you will use in real projects. ## 1) Build a list from data ```python nums = [] for i in range(5): nums.append(i*i) print(nums) ``` Better with comprehension: ```python nums = [i*i for i in range(5)] ``` ## 2) Flatten a list of lists ```python data = [[1,2], [3,4], [5]] flat = [x for row in data for x in row] print(flat) ``` ## 3) Chunk a list (split into parts) ```python items = list(range(10)) size = 3 chunks = [items[i:i+size] for i in range(0, len(items), size)] print(chunks) ``` ## 4) Remove items safely while looping (important) Wrong way: ```python # can skip items ``` Right way: ```python nums = [1,2,3,4,5,6] nums = [n for n in nums if n % 2 == 1] print(nums) ``` ## Graph: chunking ```mermaid flowchart LR A[0..9] --> B[0..2] A --> C[3..5] A --> D[6..8] A --> E[9] ``` ## Remember - Comprehensions are powerful and readable - Avoid modifying list while iterating - Chunking and flattening are common tasks