Create a map with R — rgeoapi, ggmap and ggplot2

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Improve your mapping with rgeoapi, a package designed to access the french geographic database.

rgeowhat ?

Developped by Etalab, with La Poste, l’INSEE and OpenStreetMap, the GeoAPI API is a JSON interface designed to make requests on the French geographic database.

rgeoapi was developped to facilitate your geographic projects by giving you access to these informations straight inside R. With rgeoapi, you can get any coordinate, size and population of a French city, to be used in your maps.

To install :

rinstall.packages("rgeoapi")

Get coordinates

So, let’s imagine you have a dataset with only the names of the cities you want to map. Like:

villes <- data.frame(nom = c("Rennes", "Lorient", "Brest", "Vannes"), variable1 = c("a", "b", "c", "b"), variable2 = c("Un", "Deux", "Un", "Deux"))

nom variable1 variable2
Rennes a Un
Lorient b Deux
Brest c Un
Vannes b Deux

To put these cities on a map, you’ll need their coordinates. For that, you can use rgeoapi!

library(rgeoapi)
library(plyr)
geo <- ldply(villes$nom, ComByName)

name codeInsee codeDepartement codeRegion population
Rennes 35238 35 53 211373
Rennes-le-Château 11309 11 76 58
Rennes-les-Bains 11310 11 76 258
Rennes-sur-Loue 25488 25 27 88
Rennes-en-Grenouilles 53189 53 52 117
Lorient 56121 56 53 57961
Brest 29019 29 53 139386
Brestot 27110 27 28 518
Esboz-Brest 70216 70 27 485
Vannes 56260 56 53 53032
Vannes-le-Châtel 54548 54 44 579
Pouy-sur-Vannes 10301 10 44 145
Saulxures-lès-Vannes 54496 54 44 363
Vannes-sur-Cosson 45331 45 24 589
surface lat long X_score
5035 48.11 -1.679 1
1497 42.91 2.277 0.7636
1975 42.92 2.341 0.7533
547 47.01 5.855 0.6743
801 48.49 -0.5083 0.6239
1533 47.75 -3.378 1
4948 48.4 -4.502 0.7183
884 49.34 0.6783 0.6958
977 47.8 6.441 0.4919
3313 47.65 -2.749 1
1747 48.57 5.785 0.7384
1579 48.3 3.597 0.6873
1826 48.52 5.804 0.678
3558 47.72 2.202 0.6653

 

names(villes)[1] <- "name"
villes <- merge(villes, geo, by = "name", all.x = TRUE)

Create a map with ggmap and ggplot2

The ggmap package has been designed to produce background maps to be used with ggplot2. The “fast” function to create a map is qmap(x,y) - the first argument referring to the query (city / department / region …) and the second to the zoom level of Google map.

library(ggmap)
map <- qmap('Bretagne', zoom = 8)

Once you have a map object, you can use it as the first argument of your ggplot call, and then combine it with your usual geom:

map + geom_point(data = villes, aes(x = long, y = lat, color= variable2, size = surface))

Réaliser une carte avec R, ggplot2 et rgeoapi

 

Easy, isn’t it!

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