Where should the van wait?
A made-up shop delivers to eight homes. A van can wait at two places. Where should the two places be?
Nobody has labelled the homes "north" or "south". You want the data to show its own groups. Finding groups with no labels is the job of clustering.
Key words
| Word | What it means | Example |
|---|---|---|
| Unsupervised learning | Machine learning with no right answers given. The computer finds structure itself. | Finding groups of homes |
| Cluster | A group of data points that are close or alike. | Four homes near the river |
| Clustering | Grouping data points so that points in one group are alike. | Two groups of homes |
| Centre | The average position of the points in a cluster. | The middle of one group |
| Geospatial | Data about places on the Earth. | Where each customer lives |
| Enrich | Add useful extra columns to data you already have. | Add an area name to each customer |
| Lookup table | A small table that holds extra facts about one kind of thing. | Each district and its area |
| Dataset | A set of data that is ready to be analysed. | The customers table |
| Machine learning | A part of AI where a computer finds the rule from examples. | Learning from past days |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can explain clustering and unsupervised learning, follow a simple clustering method, and enrich a dataset with place data.
Starter: last lesson
Have a go
Starter: last lesson
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
No labels, just structure
Unsupervised learning has no right answers to learn from. The computer looks at the data and finds structure on its own.
Clustering is the main kind. It groups points so that each group is alike inside and different from the others. A shop can use it to group customers who buy in similar ways.
How a clustering method works
One well known method has four steps. You choose how many groups you want, here two.
- Pick a starting centre for each group.
- Give every point to its nearest centre.
- Move each centre to the average position of its points.
- Repeat steps 2 and 3 until nothing changes.
Check: the order of the steps
Have a go
Check: the order of the steps
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.