Tutorial
Jun 26, 202610 min read
0
Unsupervised Learning and the Curse of Dimensionality
Imagine handing a model 1,797 handwritten digits and asking it to find structure — with no labels telling it which digit is which. To do anything useful (group…
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Unsupervised
Tutorial
Jun 26, 202612 min read
0
Feature Selection vs Feature Extraction
Your logistic regression on 8 diabetes features gives AUC 0.8312. Your boss asks: "Which features matter most?" You could list Glucose, BMI, and Age — each is a…
Tutorial
Jun 26, 202611 min read
0
PCA: Geometric and Math Intuition
You've got a table of 50 customer-survey questions and you need a single satisfaction score per respondent. Averaging all 50 ignores that half of them are redun…
Tutorial
Jun 26, 202610 min read
0
PCA: Eigendecomposition
The diagonal direction $[1/\sqrt{2},\ 1/\sqrt{2}]$ from post 03 captures 5.67 variance — beating either original axis. But 5.67 is not the maximum. The true opt…
Tutorial
Jun 27, 202624 min read
0
PCA: Implementation in scikit-learn
You have 64 pixel intensities per image. You know most are redundant — adjacent pixels are almost the same. How many can you drop before a model can't recognize…