A custom version of geom_rug() dash margin function (from R package ggplot2 by Hadley Wickham). The original geom_rug() makes margin dashes of unequal length depending on plot size. The current geom_rug2() was modified by user Bonded Dust as a reply to this Stackoverflow question where the issue with original geom_rug() function is also described in more detail. The function is used as a part of Tufte in R project.