Distance as Similarity

• Another simple way to gauge similarity is distance.
• It's easy to see how this would work in two dimensions.
• Plot both points, and see which is closest.
• In two dimension, distance is square-root(square(x0-x1)+square(y0-y1))
• You want to pick the smallest distance (the closest)
• If you want to make one feature more important, just multiply it by a constant greater than 1.
• Distance in two dimensions translates to N dimensions. So you can do it with 5 dimensions if you want to.
• In general the form is square-root(square(x0-x1)+square(y0-y1)+....square(n0-n1))