A data-frame with 400 rows and 3 columns (category c and coordinates x and y).
Details
This dataset generates gaussian random points with mean
equals to 1 and standard deviation equals to 0.25. Each
point has a category attribute A or B. They are centered
at (1,1) and (2,2) for category A; centered at (1,2) and
(2,1) for category B.