Plotting Cities on a GADM map with R

Question

I am trying to draw detailed maps of States/Districts of India with GADM data and using R. I have used the following code

# Load required libraries
library(sp)
library(RColorBrewer)
# ---------------------------------------------------------------------------
# load level 2 india data downloaded from http://gadm.org/country
load("IND_adm2.RData")
ind2 = gadm
# plotting districts of a State, in this case West Bengal
wb2 = (ind2[ind2$NAME_1=="West Bengal",])
spplot(wb2,"NAME_1", main = "West Bengal Districts",
       colorkey=F, scales=list(draw=T))

to generate this map

map

I am now trying to put in a couple of markers ( or points plus text ) to show district headquarters, "Purulia" at lon = 86.36521 lat = 23.33208 but somehow I am unable to get the sp.layout syntax right. I will need this for a set of towns whose long, lat will be known. Will be very grateful if someone can help me out with this.

It is not clear why you use spplot and not plot. Please provide a reproducible example, e.g. with the command that let you download the gadm data, and a command that creates Purulia. — Edzer Pebesma, May 04 '15 at 07:02

rcs · Answer 1 · 2015-05-04T09:15:17.683

Here is a short example:

library("sp")

# load level 2 india data from gadm.org
library("raster")
ind2 <- getData('GADM', country='IND', level=2)
wb2 <- ind2[ind2$NAME_1=="West Bengal",]

cities <- data.frame(name="Purulia", lon=86.36521, lat=23.33208)

spplot(wb2, "NAME_1",
       sp.layout=list("panel.points", cities$lon, cities$lat, col="red"),
       main="West Bengal Districts",
       colorkey=FALSE, scales=list(draw=TRUE))

or if you have your cities in a SpatialPointsDataFrame:

cities <- data.frame(name="Purulia", lon=86.36521, lat=23.33208)
coordinates(cities) <- ~ lon + lat
class(cities)
# [1] "SpatialPointsDataFrame"

spplot(wb2, "NAME_1",
       sp.layout=list("sp.points", cities, col="red"),
       main="West Bengal Districts",
       colorkey=FALSE, scales=list(draw=TRUE))

ssplot

This solution works well. Now I need to see how to put the city name next to the marker, but that may make the map very clumsy. Very grateful for the solution provided — Calcutta, May 04 '15 at 13:27

score 3 · Accepted Answer · answered May 04 '15 at 16:21

Here is how you can do that with base plot (instead of spplot / levelplot)

library(raster)
# get the data 
ind2 <- getData('GADM', country='IND', level=2)
wb2 <- ind2[ind2$NAME_1=="West Bengal",]
cities <- data.frame(name="Purulia", lon=86.36521, lat=23.33208)

# plot
plot(wb2, border='gray', col='light gray')
points(cities[, 2:3], col='red', pch=20)
text(cities[, 2:3], labels= cities[,1], pos=4)

Plotting Cities on a GADM map with R

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