IntermediateMatrix multiplication in NumPy: @ vs *, and the shape error everyone hits
Why A @ B and A * B give completely different answers, what "shapes not aligned" really means, and the one rule that makes matrix shapes click for good.
Library
All articles
Free to read. Filter by topic or search by title.
Browse by tag (19)
Intermediate
IntermediateBuild a chatbot that answers from your own PDFs in Python
Retrieval-augmented generation in plain Python: split a PDF into chunks, find the relevant ones, and let Claude answer using only those. No vector database required.
IntermediateGet structured JSON out of an LLM — reliably
Asking a model to reply in JSON works until it does not. Learn why tool schemas beat prompt begging, and how to validate every response before it reaches your code.
IntermediateClean a messy CSV with pandas before you train anything
Ten pandas fixes for the problems every real dataset has: broken headers, duplicate rows, mixed types, silly outliers and inconsistent categories.
IntermediateControl your volume with hand gestures using Python
Build a gesture volume controller with OpenCV and MediaPipe. Pinch your thumb and index finger together to turn the sound down, spread them apart to turn it up.
IntermediateReal-time face detection in Python: MediaPipe vs Haar cascade
Two ways to detect faces in a webcam feed with Python. See the code for both, then a straight comparison of speed, accuracy and when each one is the right choice.
IntermediateCount fingers with MediaPipe in Python
Hold up three fingers and Python says three. Learn the landmark logic behind finger counting, including the thumb rule that trips everyone up.
IntermediateBuild an AI push-up counter with pose estimation in Python
Use MediaPipe Pose to measure your elbow angle and count push-up reps automatically. The same state machine works for squats, curls and any repeated movement.
IntermediateBuild a Virtual Mouse with OpenCV and MediaPipe in Python
Learn how to build a virtual mouse in Python using OpenCV and MediaPipe hand tracking. Move the cursor with your index finger and click with a pinch — beginner-friendly step-by-step tutorial.
Newsletter
Get new articles
Free essays on learning, Python, and ML — no account required. We’ll only email when there’s something worth reading.