#2864: Compact Graphs

XKCD comic, described below.
Transcript

[Left: graph of points plotted along two axes, headered by:]

Variable 1: X Axis

Variable 2: Y Axis

[An arrow pointing to the right.]

[Right: various semi-transparent numbers in different colors stacked on top of each other, headered by:]

Variable 1: Hue

Variable 2: Label

[Caption below the panel:]

Design tip: You can make your graphs more space-efficient by using hue and label for the first two variables, instead of only turning to them once you’ve used up the X and Y axes.

(Sourced from explainxkcd.com)

People may complain about readability, but even with jpeg compression, extracting the data points is usually computationally feasible if there aren't too many of them.

ExplainOriginal