How to merge a map made with ggplot and a bubble plot in r

Question

I can produce a map of Europe and the bubble plot that would layer on top of the map but I do not know how to merge these together successfully. Will someone please help me do this? :)

Here is the code I have used to create the two separate components:

    library(cowplot)
    library(googleway)
    library(ggplot2)
    library(ggrepel)
    library(ggspatial)
    library(sf)
    library(rnaturalearth)
    library(rnaturalearthdata)    
    library("ggplot2")
    theme_set(theme_bw())
    library("sf")
    library("rnaturalearth")
    library("rnaturalearthdata")
    
    world <- ne_countries(scale = "medium", returnclass = "sf")
    class(world)
     
    ## Produces the map of Europe ##
    ggplot(data = world) +
    geom_sf() +
    coord_sf(xlim = c(-15, 55), ylim = c(34, 71), expand = FALSE)
   
             
    cities <- read.csv("cities1_R.csv")
    df <- cities
             
    df$Country <- as.factor(df$Country)
             
    head(df[ , c("City", "Country", "Latitude", "Longitude", "No..of.Samples")], 28)
             
    ## Produces Bubbles plot ##               
    ggplot(df, aes(x = Longitude, y = Latitude)) + 
    geom_polygon(df, aes(x= Longitude, y= Latitude, group=group), fill="grey", alpha=0.3)
    geom_point(aes(color = Country, size = No..of.Samples), alpha = 0.9) +
    scale_color_manual(values = c("#FF3300", "#0066CC", "#FFFF00", "#CC0066", "#9933CC", 
    "#00FFFF", "#FF9900", "#000000", "#00CC00", 
    "#999999", "#FF6666", "#FF3399", "#669933", 
    "#000099", "#6666FF", "#003300", "#66FF33", "#660066", "#FF99CC", 
    "#333333", "#CC33FF", "#CC6699", "#663300", "#330033", "#666600", "#CCFF00", "#CC9900", 
    "#990033")) +
    scale_size(breaks = c(0, 25, 50, 75, 100, 125, 150, 175), range = c(0.5, 12))  # Adjust 
    the range of points size

The size of the bubbles is dependent on the no. of samples in the cities data. This is the table: cities1_R.csv file showing the data in a table format

City	Country	Latitude	Longitude	No..of.Samples
1	AMSTERDAM	NETHERLANDS	52.37403	4.88969	22
2	BARI	ITALY	41.11148	3.53390	196
3	BUDAPEST	HUNGARY	47.49801	19.03991
4	LONDON	UNITED KINGDOM	51.50853	-0.12574
5	BERLIN	GERMANY	52.52437	13.41053
6	COPENHAGEN	DENMARK	55.67594	12.56553
7	LISBOA	PORTUGAL	38.71667	-9.13333
8	WARSZAW	POLAND	52.22977	21.01178
9	DUBLIN	IRELAND	53.33306	-6.24889
10	LJUBLJANA	SLOVENIA	46.05108	14.50513
11	BRUXELLES	BELGIUM	50.85045	4.34878
12	PARIS	FRANCE	48.85341	2.34880
13	WIEN	AUSTRIA	48.20849	16.37208
14	ASTURIAS	SPAIN	43.36140	-5.85930
15	ATHENS	GREECE	37.98380	23.72750
16	STOCKHOLM	SWEDEN	59.32930	18.06860
17	SOFIA	BULGARIA	42.69770	23.32190
18	ZAGREB	CROATIA	45.81500	15.98190
19	NICOSIA	CYPRUS	35.18560	33.38230
20	PRAGUE	CZECH REPUBLIC	50.07550	14.43780
21	TALLINN	ESTONIA	59.43700	24.75360
22	HELSINKI	FINLAND	60.16990	24.93840
23	RIGA	LATVIA	56.94960	24.10520
24	VILNIUS	LITHUANIA	54.68720	25.27970
25	LUXEMBOURG CITY	LUXEMBOURG	49.81530	6.12960
26	VALLETTA	MALTA	35.89890	14.51460
27	BUCHAREST	ROMANIA	44.42680	26.10250
28	BRATISLAVA	SLOVAKIA	48.14860	17.10770

This is the map of Europe I have produced: Map of Europe

This is the bubble plot I have produced: Bubble ggplot

If someone knows how to merge the two ggplots that would be amazing. I tried using the geom_polygon function but I couldn't get it to work. Thank you in advance!

Could you please make it into a reproducible example? If you add a hard-coded version of your dataframe loaded from the CSV with just a couple of rows it would make it a lot easier for anyone to run your code, — Leonardo Viotti

Leonardo Viotti Leonardo Viotti · Accepted Answer · 2021-03-09T20:11:10

I added a rough version of a repex with just 3 cities, but this should work with your entire data.

library(cowplot)
library(googleway)
library(ggplot2)
library(ggrepel)
library(ggspatial)
library(sf)
library(rnaturalearth)
library(rnaturalearthdata)    
library("ggplot2")
theme_set(theme_bw())
library("sf")
library("rnaturalearth")
library("rnaturalearthdata")

x = "1 AMSTERDAM NETHERLANDS 52.37403 4.88969 22

7 LISBOA PORTUGAL 38.71667 -9.13333 12

3 BUDAPEST HUNGARY 47.49801 19.03991 0"


df <- read.table(text=x, 
                 header = F,
                 col.names=c('idx', 'City', 'Country', 'Latitude',  'Longitude', 'No..of.Samples'))

world <- ne_countries(scale = "medium", returnclass = "sf")
class(world)

## Produces the map of Europe ##
ggplot(data = world) +
  geom_sf() +
  geom_point(df, 
             mapping = aes(x= Longitude, y= Latitude,  size = No..of.Samples, color = Country), 
             fill="grey", alpha=0.3) + 
  coord_sf(xlim = c(-15, 55), ylim = c(34, 71), expand = FALSE)

It outputs:

How to merge a map made with ggplot and a bubble plot in r

1 Answers