Introduction to Geospatial Visualization with the tmap package

Introduction to Geospatial Visualization with the tmap package: Geospatial visualization is a powerful tool for exploring and communicating patterns and trends in spatial data. The tmap package in R provides an easy-to-use framework for creating high-quality static and interactive geospatial visualizations. In this introduction, we'll cover some basic concepts and examples to get you started with using tmap for your own data visualizations.

Basic tmap syntax

The basic syntax of tmap is simple and intuitive. Here's an example of how to create a map of the United States with some sample data:

library(tmap) data("World") states <- World[World$region == "USA", ] tm_shape(states) + tm_polygons("HPI", palette = "Blues")

In this code, we’re loading the tmap library, then loading the World dataset that comes with the package. We're selecting just the data for the United States, and then creating a tmap object with tm_shape(). Finally, we're adding a layer to the map with tm_polygons(), which displays the "HPI" variable (which stands for "Human Poverty Index") using a blue color palette.

Mapping point data

tm_points() can be used to create point-based maps. Here's an example:

library(sp) data(meuse) coordinates(meuse) <- ~x+y tm_shape(meuse) + tm_dots("cadmium", palette = "Blues")

This code is using the meuse dataset, which is included with the sp package. We're setting the x and y coordinates of the data using the coordinates() function, and then creating a tmap object with tm_shape(). Finally, we're adding a layer to the map with tm_dots(), which displays the "cadmium" variable using a blue color palette.

Mapping raster data

tm_raster() can be used to create raster-based maps. Here's an example:

library(raster) data(volcano) r <- raster(volcano) tm_shape(r) + tm_raster(palette = "-Blues")

This code is using the volcano dataset, which is included with the raster package. We're creating a raster object with the raster() function, and then creating a tmap object with tm_shape(). Finally, we're adding a layer to the map with tm_raster(), which displays the raster data using a blue color palette.

Interactive maps

tmap also supports creating interactive maps using the tmap_leaflet() function. Here's an example:

library(leaflet) tm_shape(states) + tm_polygons("HPI", palette = "Blues") + tmap_leaflet()

This code is creating the same map as before, but adding tmap_leaflet() at the end to create an interactive map using the leaflet library.

In this introduction, we covered some basic concepts and examples for creating geospatial visualizations using the tmap package in R. With just a few lines of code, you can create high-quality static and interactive maps of your spatial data. For more information on using tmp, see the package documentation and tutorials.

Read more: Geographic Data Science with R

Originally published at https://pyoflife.com on April 4, 2023.