What is Linear Discriminant Analysis (LDA), and how does it differ from PCA?

LDA is the supervised cousin of PCA, and the contrast is a favorite. The signal is knowing that LDA spends the labels to maximize class separation while PCA only chases variance, plus the C minus 1 dimension cap that catches most candidates off guard.

Updated Aug 2026 · Grounded in real Applied AI Engineer interview loops and written to a senior-engineer editorial bar.