Unsupervised learning: basics

Cluster Analysis in Python

Shaumik Daityari

Business Analyst

Everyday example: Google news

How does Google News classify articles?
Unsupervised Learning Algorithm: Clustering
Match frequent terms in articles to find similarity

Labeled and unlabeled data

Data with no labels

Point 1: (1, 2)
Point 2: (2, 2)
Point 3: (3, 1)

Data with labels

Point 1: (1, 2), Label: Danger Zone
Point 2: (2, 2), Label: Normal Zone
Point 3: (3, 1), Label: Normal Zone

What is unsupervised learning?

A group of machine learning algorithms that find patterns in data
Data for algorithms has not been labeled, classified or characterized
The objective of the algorithm is to interpret any structure in the data
Common unsupervised learning algorithms: clustering, neural networks, anomaly detection

What is clustering?

The process of grouping items with similar characteristics
Items in groups similar to each other than in other groups
Example: distance between points on a 2D plane

Plotting data for clustering - Pokemon sightings

from matplotlib import pyplot as plt

x_coordinates = [80, 93, 86, 98, 86, 9, 15, 3, 10, 20, 44, 56, 49, 62, 44]
y_coordinates = [87, 96, 95, 92, 92, 57, 49, 47, 59, 55, 25, 2, 10, 24, 10]

plt.scatter(x_coordinates, y_coordinates)
plt.show()

Up next - some practice

Cluster Analysis in Python