Getting an appropriate basemap is an essential first step in the map making process. The examples shown in this gallery show some of the variety you can get by using fairly simple R code.
Later, you’ll see that the specification of a basemap is made easier by using some functions. Here, we’re only focused on the general appearance of the basemaps. These examples will help you decide what type of basemap will best suit your project.
Each section has its own setup and default information. This allows each section to be run independently. The duplication of code is a small price to be paid for the independence and clarity achieved by this repetition.
All use of Google maps requires the use of an API key. Getting this key is a one-time task. Store the key somewhere same and hidden from the outside.
Registering the Google Key needs to be done once each session.
## Libraries
library(readr)
library(ggmap)
library(ggplot2)
library(sitemaps)
## Initialize Google Map key; the is stored in a Project directory.
My_Key <- read_file("P://Hot/Workflow/Workflow/keys/Google_Maps_API_Key.txt")
## Test if Google Key is registered
if (!has_google_key()){
## Register the Google Maps API Key.
register_google(key = My_Key, account_type = "standard")
} ## end Google Key testIt is essential to include the code to set the parameters (site_styles()) and the Google Map hide codes (site_google_hides()).
This code block also defines a simple theme that removes the geographic coordinates from the map borders, places a black line around the map, and suppresses a default legend.
## Read in all the parameters
column <- site_styles()
hide <- site_google_hides()
#################################################################
## Define a theme that removes the axis labels and
## puts a border around the map. No legend.
simple_black_box <- theme_void() +
theme(panel.border = element_rect(color = "black",
fill=NA,
size=2),
legend.position = "none")The Google basemaps have annotations on top. There are ways to selectively limit the annotation. This capability is discussed later along with a few other features that make these maps more useful.
| Map Type | Appearance |
| roadmap | Street map |
| terrain | Shaded relief map |
| satellite | Satellite image |
| hybrid | Satellite image and street map |
Here are a few examples that show some of the types of base maps. Note that the theme (“simple_black_box”), defined earlier, is used to simplify these maps.
map2 <- get_map(location = "Island of Oahu, Hawaii, USA",
zoom=10,
source="google",
maptype="roadmap")
ggmap(map2) + simple_black_box
map3 <- get_map(location = "Island of Oahu, Hawaii, USA",
zoom=10,
source="google",
maptype="terrain")
ggmap(map3) + simple_black_box
map5 <- get_map(location = "Island of Oahu, Hawaii, USA",
zoom=10,
source="google",
maptype="satellite")
ggmap(map5) + simple_black_box
map1 <- get_map(location = "Island of Oahu, Hawaii, USA",
zoom=10,
source="google",
maptype="hybrid")
ggmap(map1) + simple_black_box
It is possible to “hide” different layers of annotations on Google Maps. This example (Figure 5), which shows the hide$all parameter is just one possibility. See the Google Maps Simplified section for examples of alternative layer hiding.
map <- get_googlemap(center = "Island of Oahu, Hawaii, USA",
zoom=10,
maptype="terrain",
style=hide$all)
ggmap(map) + simple_black_box
The large property shown in this example (Figure 6) houses the Huntington Library, Art Gallery and Botanical Garden. Zooming out, you see the surrounding neighborhood (Figure 7) and, with even more zoom, the city is shown (Figure 8) next to the adjacent mountains. Finally (Figure 9) you see much of the Los Angeles basin. The original site is now too small to be seen.
map10 <- get_map(location = c(lon=-118.11418, lat=34.12839),
zoom=16,
source="google",
maptype="terrain")
ggmap(map10) + simple_black_box
map11 <- get_map(location = c(lon=-118.11418, lat=34.12839),
zoom=14,
source="google",
maptype="terrain")
ggmap(map11) + simple_black_box
map12 <- get_map(location = c(lon=-118.11418, lat=34.12839),
zoom=12,
source="google",
maptype="terrain")
ggmap(map12) + simple_black_box
map13 <- get_map(location = c(lon=-118.11418, lat=34.12839),
zoom=10,
source="google",
maptype="terrain")
ggmap(map13) + simple_black_box
Similarly, the Stamen maps have very different appearances. These alternatives are shown in the next set of maps.
Some of the basemap alternatives, such as “watercolor,” (Figure 15) are very creative and might be interesting to use for non-technical applications.
In practice, Stamen maps of large areas may involve considerable downloading. It is suggested that they only be used for smaller areas.
| Map Type | Appearance |
|---|---|
| terrain-background | Terrain without names |
| terrain | Mountains with hill-shading, colored vegetation, and names |
| toner | Black & white, minimalist without names |
| toner-background | Black & white, minimalist without names |
| toner-lite | Grey & white, minimalist with names |
| watercolor | Colorful, abstract, without streets, place names, or borders |
map8 <- get_map(location="Japan",
zoom=5,
source="stamen",
maptype="terrain-background")
ggmap(map8) + simple_black_box
map9 <- get_map(location="Japan",
zoom=5,
source="stamen",
maptype="terrain")
ggmap(map9) + simple_black_box
map12 <- get_map(location="Japan",
zoom=5,
source="stamen",
maptype="toner")
ggmap(map12) + simple_black_box
map13 <- get_map(location="Japan",
zoom=5,
source="stamen",
maptype="toner-background")
ggmap(map13) + simple_black_box
map10 <- get_map(location="Japan",
zoom=5,
source="stamen",
maptype="toner-lite")
ggmap(map10) + simple_black_box
map14 <- get_map(location="Japan",
zoom=5,
source="stamen",
maptype="watercolor")
ggmap(map14) + simple_black_box
These maps give a lot of options when you’re choosing a basemap.
Maps that don’t have names can be given the place names you want. This is an important part of the process in creating a custom map that best serves your visualization requirements.
There is a detailed treatment giving names in a later chapter (Chapter 6: Names). Here is a simple demonstration (Figure 16) that uses the last map (Figure 15).
You can see (in the code) that the names are provided in a table along with coordinate locations and a few style parameters. How these column values work will be explained later.
map14names <- read_csv(col_names = TRUE, file =
"text, lat, lon, name_text_wrap, fontface
Tokyo, 35.68668, 139.77796, NA, plain
Kyoto, 35.01866, 135.76851, NA, plain
Hiroshima, 34.45604, 132.47520, NA, plain
Sapporo, 43.14579, 141.34479, NA, plain
Sea of Japan, 39.94473, 134.04759, 9, italic
Pacific Ocean, 30.91643, 140.34591, 9, italic")
ggmap(map14) +
site_names(datatable = map14names) +
simple_black_box