How to plot location dots on a country map in r? - r

Question

I searched already a lot for my specific problem but could not find a solution. Although, I think it is quite easy to solve, but I am new to r.
What i want to do: I would like to plot a map of India held in black and white. And I want to plot all the places I visited with dots and the corresponding name. I managed to do all that with the code below.
My problem: How can I write the code in a simpler way for plotting the visited places? I don't want to create all the variables like visit.x and visit.y. Further, I would have to write for every place the code for geom_point and geom_text. When I tried to plot more than one place at once with e.g.
visited <- c("New Delhi", "Rishikesh")
then I got the error message "Aesthetics must be either length 1 or the same as the data".
My question: How can I just store all the visited places in one variable and plot it in one run? Like that I just need one line for geom_point and not for every place I want to plot.
#Load required packages
library(maps)
library(ggmap)
library(ggplot2)
#Dataframe with country relevant information
map <- fortify(map(fill = T, plot = F, region = "India"))
#Places I want to mark on the map
visited <- c("New Delhi")
visited2 <- c("Rishikesh")
visited3 <- c("Agra")
#Extracting long / lat of the places
visit.x <- geocode(visited)$lon
visit.y <- geocode(visited)$lat
visit.x2 <- geocode(visited2)$lon
visit.y2 <- geocode(visited2)$lat
visit.x3 <- geocode(visited3)$lon
visit.y3 <- geocode(visited3)$lat
#Defining font
font = c("Courier")
font.size = 3
#Specifing the look of the map with ggplot2
map_india <- ggplot(data = map, aes(x = long, y = lat, group = group)) +
geom_polygon(fill = "white") +
geom_path(colour = "black") +
theme(panel.background = element_rect(fill = "#000000"),
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
axis.ticks = element_blank(),
axis.text.y = element_blank(),
axis.text.x = element_blank(),
axis.title.x = element_blank(),
axis.title.y = element_blank())
#Plotting the places I want on the map with labels
map_india <- map_india +
geom_point(aes(x = visit.x, y = visit.y)) +
geom_text(data = NULL, x = visit.x - 1, y = visit.y + 0.2, label = "New Delhi", size = font.size, family = font) +
geom_point(aes(x = visit.x2, y = visit.y2)) +
geom_text(data = NULL, x = visit.x2 - 1, y = visit.y2 + 0.2, label = "Rishikesh", size = font.size, family = font) +
geom_point(aes(x = visit.x3, y = visit.y3)) +
geom_text(data = NULL, x = visit.x3, y = visit.y3 + 0.5, label = "Agra", size = font.size, family = font) +
coord_fixed(0.8)
#Creating pdf
pdf("India.pdf", height = 11.69, width = 16.53)
print(map_india)
dev.off()

Answer 1

As #hrbrmstr suggested in the comment above, ggplot2 is designed to work with data.frames, so it works best to keep your data in one throughout. Doing so actually simplifies the code a lot, too:
library(tidyverse) # for ggplot2 and `%>%`
library(ggmap)
library(ggrepel) # for geom_text_repel, though adjust overlaps manually if you prefer
cities <- data_frame(city = c("New Delhi", "Rishikesh", "Agra")) %>% # start data.frame
mutate_geocode(city) # use ggmap function to add lon/lat columns
cities
#> # A tibble: 3 × 3
#> city lon lat
#> <chr> <dbl> <dbl>
#> 1 New Delhi 77.20902 28.61394
#> 2 Rishikesh 78.26761 30.08693
#> 3 Agra 78.00807 27.17667
box <- geocode('India', output = 'more') # get lon/lat for bounding box
box
#> lon lat type loctype address north south east
#> 1 78.96288 20.59368 country approximate india 35.5087 6.753516 97.39556
#> west country
#> 1 68.16289 India
get_stamenmap(bbox = c(left = box$west, # get background tiles, set bounding box
bottom = box$south,
right = box$east,
top = box$north),
maptype = 'toner-background', # set map style
zoom = 5) %>%
ggmap(extent = 'device') + # note switch from %>% to + as moves to ggplot
geom_point(aes(x = lon, y = lat), data = cities) + # add points
geom_text_repel(aes(x = lon, y = lat, label = city), data = cities) # add labels
Adjust as you like.