# Unsupervised

> Unsupervised learning concepts

- Skill: `ffsshhttiikk/unsupervised` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ffsshhttiikk/unsupervised`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ffsshhttiikk/unsupervised/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MIT
- Author: ffsshhttiikk (https://skillmd.com/u/ffsshhttiikk)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ffsshhttiikk/unsupervised

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## What I do

- Discover hidden patterns in data
- Group similar observations without labels
- Reduce feature dimensions
- Find outliers and anomalies
- Learn latent representations
- Generate synthetic data

## When to use me

Use me when:
- Labels are unavailable or expensive
- Exploring unknown data patterns
- Reducing data complexity
- Preprocessing for supervised learning
- Real-time clustering needed

## Key Concepts

### Clustering
- **K-Means**: Centroid-based, assumes spherical clusters
- **Hierarchical**: Dendrogram-based, any distance
- **DBSCAN**: Density-based, finds arbitrary shapes
- **GMM**: Probabilistic, soft clustering

### Dimensionality Reduction
- **PCA**: Linear, variance-based
- **t-SNE**: Non-linear, visualization
- **UMAP**: Non-linear, structure preservation
- **Autoencoders**: Non-linear, learned

### Evaluation
- Silhouette score
- Davies-Bouldin index
- Calinski-Harabasz index
- Reconstruction error (for autoencoders)