Customizing Popup in DataMaps

This is a short demo on how to customize the popup on hover in DataMaps using rMaps (v > 0.1.1)

Let us start by creating a simple choropleth map of crime rates

library(rMaps)
crime2010 = subset(violent_crime, Year == 2010)
choro = ichoropleth(Crime ~ State, data = crime2010)

You can customize the popup using the popupTemplate option in DataMaps. The popupTemplate accepts a function with two arguments. The geography argument pertains to the topojon map file, while the data argument refers to the dataset that has been passed to DataMaps. This function returns a string. In the example below, I have customized the popupTemplate to display the state name using geography.properties.name and the crime rate using data.Crime.

choro$set(geographyConfig = list(
  popupTemplate = "#! function(geography, data){
    return '<div class=hoverinfo><strong>' + geography.properties.name + 
      ': ' + data.Crime + '</strong></div>';
  } !#" 
))

You can also create the popup in R if you are more comfortable doing that.

crime2010 = transform(crime2010, 
  popup = sprintf("<strong>State:</strong> %s <br/><strong>Crime:</strong> %s", 
    State, Crime
  ) 
)

You can now pass this on to popupTemplate.

choro$set(geographyConfig = list(
  popupTemplate = "#! function(geography, data){
    return '<div class=hoverinfo>' + data.popup + '</div>';
  } !#" 
))
choro

I plan to make it simpler to handle popups in the next version of rMaps, so that you will be able to pass a mustache template and not have to bother with javascript.