color points on plot depending of a value of a column

Question

I have a dataset with 2 columns. With plot(ds$values) I get all the points in black.

Now consider that I have one second column that gives me categories as strings. Notice that I don't know the categories names. How do I plot each category with a different colour.

A simple: plot(ds$values, col=someFn(ds$categories))?

Adding an index would be good but not required.

Answer 1

The key here is to transform your categorical variable from character to factor. You can simply wrap it in factor as you pass it to the col argument in plot. Here's a simple example:

set.seed(1)
plot(sample(1:10,20,TRUE), col=factor(sample(letters[1:3],20,TRUE)))

Of course, you may want to pick a different color palette than the default.