Maps 2 EPID 799C Fall 2017 To code along today: Have a county dataframe with FIPS Download Install packages galore: sp, rgdal, rgeos, tmap,

Today: Maps in R Quick Review Getting spatial data Read / write Merge Vis packages Data structures (sp/sf) Basic spatial operations Example map projects

Review from last time Types: Point, Line, Poly, Raster Shapefile structure QGIS Basics

Getting spatial data Tiger Files: https://www.census.gov/geo/maps- data/data/tiger-line.html NC One Map http://data.nconemap.gov/geoportal/catalog/main /home.page Geocode your own

Read/write ReadOGR writeOGR

Merge Exactly the same as spatial! (Thanks, overloading) new_df = merge(df1, df2) # by=… and all.x/all.y= parameters Important! 1. Do not merge the data by itself. I have done this. 2. Also: joining data can be a pain

Viz Packages base::plot() sp::spplot() ggplot tmap

Side note: There’s a new structure in town! Simple features (sf) spec – just a dataframe! The spatial information is stored as another “variable’ Not quite as efficient in some ways, but easier to work with. Can eventually overload dplyr functions. See cran page and many vignettes

Basic Spatial Operations spTransform() http://www.epsg.org/ , cheat sheet, spatial reference list gCentroid() gRelates() DE-9IM matrix gTouches() ^simple version of above aggregate() (spatial) gBuffer() over() and %over%  workhorse. (SE example here) gDist() spSample … and many more

Let’s Try! Prepare your county tbl

Map Project Examples Title VI complaint Flood plain mapping Alcohol exposure index Linking police killing Police traffic stops / police