Geographic Coordinate

Geographic coordinate uses latitude and longitude to locate a position.
Latitude and longitude are just like x-y axes, so you can build all kinds of graphs with them, like Scatterplot and Density Contour Plot.

• In a geographic coordinate, latitude comes first. But it is the north-south direction. Therefore, there is a cross between lat-long and x-y coordinates.
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There are also some special graphs for geographic coordinate system, but with controversial performance, like

• [-] Radius Map: use a circle with a radius dependent on an additional variable to represent a dot
• [-] Push Pin Map: use a push pin icon to represent a dot

Implementation

ggmap

Package ggmap can generate real-world maps. It is compatible with ggplot2, so you can easily add layers on top of the base map. Related functions:

• get_stamenmap: get a US map
  • can be zoomed using option bbox, zoom, and the latitude-longitude range of the area
• get_googlemap: get the map of the specified latitude-longitude range from Google map
• ggmap: render the map

sf and tmap

by zcysxy