For maps, refer to the following resources:
Function
borders(): http://docs.ggplot2.org/current/borders.htmlFunction
coord_map(): http://docs.ggplot2.org/current/coord_map.htmlHelp page of the function
map_data(): http://docs.ggplot2.org/current/map_data.htmlggmap: Spatial Visualization with ggplot2, The R Journal Vol. 5/1, D. Kahle and H. Wickham
For GGally, refer to the following resources:
For Heatmaps, refer to the following resources:
Help page of the function
geom_tile(): http://docs.ggplot2.org/current/geom_tile.html