Meaning of unscaled x, x2 and y, y2

[lionel-]

In Vega, the unscaled (x, y) point represents the top left corner and (x2, y2) the bottom right corner. This may make sense from the perspective of a web developer, but I think it's not so intuitive for statisticians and data analysts who are used to work with cartesian axes.

Maybe their meaning could be redefined in the ggvis DSL: (x, y) for the bottom left corner and (x2, y2) for the top right corner?