Scatter Plots on Maps in ggplot2

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

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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)