graphics, grDevices, dplyr, RColorBrewer, KernSmooth, proj4,
scales, grid, gtable, ash, maps, MASS
utils, graphics, grDevices, dplyr, RColorBrewer, KernSmooth,
proj4, scales, grid, gtable, ash, maps, MASS, extrafont,
tibble, plotly (>= 3.4.1)
testthat, gridExtra, knitr, rmarkdown, ggthemes
testthat, gridExtra, knitr, rmarkdown, ggthemes, reshape2