Choropleth maps

Interactive Data Visualization with plotly in R

Adam Loy

Statistician, Carleton College

Choropleth maps in plotly

head(turnout)

       state state.abbr turnout2018 turnout2014  ballots      vep      vap
1    Alabama         AL       0.474       0.332  1725000  3641209  3802714
2     Alaska         AK       0.537       0.548   280000   521777   554426
3    Arizona         AZ       0.486       0.341  2385000  4910625  5519036
4   Arkansas         AR       0.412       0.403   895000  2171940  2319740
5 California         CA       0.478       0.307 12250000 25635139 30836229
6   Colorado         CO       0.619       0.547  2540000  4103903  4445013

Choropleth maps in plotly

turnout %>%

  plot_geo(locationmode = 'USA-states') %>%

  add_trace(
    z = ~turnout,                   # Sets the color values
    locations = ~state.abbr         # Matches cases to polygons
  ) %>%

  layout(geo = list(scope = 'usa')) # Restricts map only to USA

Limitation of plot_geo()

locationmode: "USA-states" | "ISO-3" | "country names"

Mapping options

scope = "usa"

"world" | "usa" | "europe" | "asia" | "africa" | "north america" | "south america"

projection = list(type = "mercator")

"conic conformal" | "mercator" | "robinson" | "stereographic" | and 18 more...

scale = 1

Larger values = tighter zoom

center = list(lat = ~c.lat, lon = ~c.lon)

Set c.lat and c.lon to center the map

Let's get mapping!

Interactive Data Visualization with plotly in R