Scatter Plots on Maps in ggplot2

How to make Scatter Plots on Maps plots in ggplot2 with Plotly.

New to Plotly?

Plotly is a free and open-source graphing library for R. We recommend you read our Getting Started guide for the latest installation or upgrade instructions, then move on to our Plotly Fundamentals tutorials or dive straight in to some Basic Charts tutorials.

Default map plot

library(plotly)

## Loading required package: ggplot2

## 
## Attaching package: 'plotly'

## The following object is masked from 'package:ggplot2':
## 
##     last_plot

## The following object is masked from 'package:stats':
## 
##     filter

## The following object is masked from 'package:graphics':
## 
##     layout

p <-    
 if (require("maps")) {
  ia <- map_data("county", "iowa")
  mid_range <- function(x) mean(range(x))
  seats <- do.call(rbind, lapply(split(ia, ia$subregion), function(d) {
    data.frame(lat = mid_range(d$lat), long = mid_range(d$long), subregion = unique(d$subregion))
}))

ggplot(ia, aes(long, lat)) +
  geom_polygon(aes(group = group), fill = NA, colour = "grey60") +
  geom_text(aes(label = subregion), data = seats, size = 2, angle = 45)
}

## Loading required package: maps

plotly::ggplotly(p)

Add capital cities data

library(plotly)

p <-    
 if (require("maps")) {
  data(us.cities)
  capitals <- subset(us.cities, capital == 2)
  ggplot(capitals, aes(long, lat)) +
    borders("state") +
    geom_point(aes(size = pop)) +
    scale_size_area() +
    coord_quickmap()
}

plotly::ggplotly(p)

Add more map data to the plot

library(plotly)

p <-    
 if (require("maps")) {
  data(us.cities)
  capitals <- subset(us.cities, capital == 2)
  ggplot(capitals, aes(long, lat)) +
    borders("world", xlim = c(-130, -60), ylim = c(20, 50)) +
    geom_point(aes(size = pop)) +
    scale_size_area() +
    coord_quickmap()
}

plotly::ggplotly(p)

What About Dash?

Dash for R is an open-source framework for building analytical applications, with no Javascript required, and it is tightly integrated with the Plotly graphing library.

Learn about how to install Dash for R at https://dashr.plot.ly/installation.

Everywhere in this page that you see fig, you can display the same figure in a Dash for R application by passing it to the figure argument of the Graph component from the built-in dashCoreComponents package like this:

library(plotly)

fig <- plot_ly() 
# fig <- fig %>% add_trace( ... )
# fig <- fig %>% layout( ... ) 

library(dash)
library(dashCoreComponents)
library(dashHtmlComponents)

app <- Dash$new()
app$layout(
    htmlDiv(
        list(
            dccGraph(figure=fig) 
        )
     )
)

app$run_server(debug=TRUE, dev_tools_hot_reload=FALSE)