Visualizing Geographic Data

with geofacet

Hafen Consulting, LLC

 

@hafenstats

Ryan Hafen

Example

> state_unemp
# A tibble: 867 x 3
    year  rate state
   <int> <dbl> <chr>
 1  2000   4.6 AL   
 2  2001   6   AL   
 3  2002   5.8 AL   
 4  2003   6   AL   
 5  2004   5.2 AL   
 6  2005   4.2 AL   
 7  2006   3.9 AL   
 8  2007   4.4 AL   
 9  2008   8.3 AL   
10  2009  11.8 AL   
# … with 857 more rows

 

How does unemployment vary geographically and over time?

 

US annual unemployment rates by state from 2000 to 2016

Choropleth of 2016 Unemployment

  • Small regions are hard to see (can you see DC?)
  • Color isn't ideal for making judgements of magnitude of difference
  • Can't see over time

"statebin" of 2016 Unemployment

  • Small regions are hard to see (can you see DC?)
  • Color isn't ideal for making judgements of magnitude of difference
  • Can't see over time

Faceting by state

  • Difficult to make judgements about geographic similarities / differences
ggplot(state_unemp, aes(year, rate)) +
  geom_line() +
  facet_wrap(~ state)

What if we try to rearrange the panels to mimic the general layout of the states?

install.packages("geofacet")
library(geofacet)

This is very easy to do with geofacet

+

Geofaceting by state

ggplot(state_unemp, aes(year, rate)) +
  geom_line() +
  facet_geo(~ state, grid = "us_state_grid1")

Creating Your Own Grids

  • grid_auto() can take a shape file and provide a first pass at a grid layout that resembles the underlying geography
  • grid_design() provides an interactive interface to tweak a grid layout provided by grid_auto(), or allows you to start from scratch
install.packages("USAboundaries")

# get Washington county boundaries from USAboundaries package
counties <- USAboundaries::us_counties(states = "washington")

# convert to SpatialPolygonsDataFrame
counties <- as(counties, "Spatial")

# remove unneeded columns
counties@data <- counties@data[, c("countyfp", "name")]

# this gives counties good initial approximation
grd <- grid_auto(counties, seed = 1234)

 

Example: Counties in Washington

grid_preview(grd, label = "name_name")

Example: Counties in Washington

grid_design(grd, label = "name")

A Collection of Grids

And More to Come...

(I need some help)

For More Information

geofacet

By Ryan Hafen

geofacet

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