Features as Coordinates

Lesson 2 of 10 · 7 min · Free, no account needed

What you will learn

A feature is a number measured from a thing, like weight or redness.
Two features give every thing an address: a point in the feature space.
Similar things land close together, so a new thing can be read by its neighbors.
The label is the answer. It hangs on the point, it is not one of its coordinates.

A computer has no eyes. It only gets numbers.
A fruit sorter must tell an apple from a lime. Which two tools would you give it? Tap two, then Check.
Watch the sorter measure, then turn fruit into points.
Drag the time slider, or press Play. Weight goes across, redness goes up.
Your apple weighs 160 g and is 80% red. Put it on the map.
Drag it to its spot. This apple stays yours for the rest of the lesson.
A cherry: 10 g and 90% red. Where will it land?
Tap the part of the map before it flies in.
What you just did has names.
Tap to reveal them.
A number you measure from a thing is a feature. Here: weight and redness.
Each thing becomes a point. The map where the points live is the feature space.
Similar things land close together. Near means similar, and that's what a machine uses.
Game: Mystery fruit. Get 5 in a row.
A ? point appears. Tap the cloud of fruit it belongs to. Its nearest neighbors give it away.
A pear arrives with four facts. Where does each one go?
Drag each chip to a slot: across, up, the point's label, or another feature this map doesn't show.
Messages can be points too. Feed two to a counting program.
Drag a message onto the program. It walks the words one by one and counts two features.
A music app wants to learn which songs you like.
Try both pairs of features. Then tap the map the app should use, and Check.
Speed round: flick three fruits into their clouds.
Press Start. You get 3 seconds each. Your apple from earlier is the last one.

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