t-SNE maps high-dimensional points to 2D by preserving local neighborhood structure. Similar points are pulled together; dissimilar ones are pushed apart.
Perplexity controls how many neighbors each point considers - lower = tighter, isolated clusters.
UMAP uses a different graph-based objective and often preserves global structure better.
t-SNE and UMAP are nonlinear dimensionality reduction methods that project high-dimensional data into 2D for visualization. t-SNE minimizes KL divergence between pairwise similarity distributions in high-D and low-D space - it excels at revealing cluster structure but distorts global distances. UMAP is faster, preserves more global structure, and scales to millions of points while producing similarly tight cluster separations.
See the 2D projection update as you change t-SNE perplexity - low perplexity reveals fine local structure, high perplexity shows global layout
Compare t-SNE vs UMAP on the same dataset - UMAP runs 10-100x faster and preserves inter-cluster distances better
Understand why t-SNE cluster sizes and distances are NOT meaningful - only topology (which groups are separate) can be interpreted
Adjust UMAP n_neighbors: small values focus on local structure, large values preserve global topology
Learn the crowding problem t-SNE solves: using t-distribution (heavy tails) in low-D space to prevent cluster collapse
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