Sets vpc rug layer
pmx_vpc_rug(show = TRUE, color = "#000000", size = 1, alpha = 0.7)logical If TRUE show bin separators
character Color of the rug. Default: "#000000".
numeric Thickness of the rug. Default: 1.
numeric Transparency of the rug. Default: 0.7.
When the vpc confidence interval layer method is rectangles we don't show rug separators.
Other vpc: pmx_plot_vpc,
pmx_vpc_bin, pmx_vpc_ci,
pmx_vpc_obs, pmx_vpc_pi,
pmx_vpc