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

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

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

4. Getting spatial data
Tiger Files: data/data/tiger-line.html
NC One Map /home.page
Geocode your own

5. Read/write
ReadOGR
writeOGR

6. 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

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

8. 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

9. Basic Spatial Operations
spTransform() , 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

10. Let’s Try!
Prepare your county tbl

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