Correlation analysis in R

http://www.sthda.com/english/wiki/correlation-matrix-a-quick-start-guide-to-analyze-format-and-visualize-a-correlation-matrix-using-r-software?utm_content=buffer7c125&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Sorting data frames in R

http://www.r-bloggers.com/how-to-sort-a-list-of-dataframes/
good post talking about this

Processing spatial data in R

Resources online that are good references:

https://dl.dropboxusercontent.com/u/24648660/ggmap%20useR%202012.pdf


A great post talking about using R as a GIS.

https://github.com/Pakillo/R-GIS-tutorial

This is another great post introducing making maps using ggplot2:
http://www.molecularecologist.com/2016/07/making-maps-in-r-volume-2-ggplots/

http://urbandemographics.blogspot.co.uk/2016/04/creating-tilted-and-stacked-maps-in-r.html