How to use multiple data frame inputs for Mapdeck add_scatterplot within R Shiny?

Question

I'm finding Mapdeck to be a really cool alternative mapping method when working with large datasets in r shiny. However I'm finding it difficult to pass in multiple datasets in order to expand the complexity of the resulting map.

For Example: I'm trying to populate the tooltip to create a popup with 'two' items by pulling in information from a second data frame (to illustrate a 1-to-many relationship). But I can't get it to work. Any thoughts?

Data sample

Map_DF <- data.frame("Point_ID" = 1:3, "Latitude" = c(38.05, 39.08, 40.05), "Longitude" = c(-107.00, -107.05, -108.00))
PointUse_DF <- data.frame("Point_ID" = c(1, 1, 2, 2, 3), "PointUse" = c("farm", "house", "farm", "house", "farm"))

The Code.

# ################################################################################################
# ################################################################################################
# # Sec 1a. Needed Libaries & Input Files

library(shiny)
library(shinydashboard)
library(mapdeck)
library(dplyr)


################################################################################################
################################################################################################
#UI
ui <- dashboardPage(
    dashboardHeader(), 
    dashboardSidebar(), 
    dashboardBody(
        mapdeckOutput(outputId = 'mapA')
    )
)

################################################################################################
################################################################################################
server <- function(input, output) {


    ##The MapDeck Token
    key <- '## put your own token here ##'
    set_token(key) ## set your access token


    ### The Map
    output$mapA <- renderMapdeck({
     mapdeck() %>%
            add_scatterplot(
                data = Map_DF, 
                lat = "Latitude",
                lon = "Longitude",
                layer_id = 'Point_ID',
                tooltip = c("Point_ID",
                             PointUse_DF$PointUse[Map_DF$Point_ID]  # the idea of passing in a a key and returning multiple items
                            )
             )
    })

}

################################################################################################
################################################################################################
shinyApp(ui = ui, server = server)

Answer 1

The tooltip renders a column of the data object inside the popup. So whatever you want displayed in the popup has to already exist on the data

with your example you need to create the tooltip column

# Using data.table to rshape the data to give a comma-separated list of 'PointUse' values
library(data.table)

dt <- setDT( PointUse_DF )[, .(info = paste0(PointUse, collapse = ", ")), by = Point_ID]

## Now you can put this onto the map object

Map_DF <- merge(
  x = Map_DF
  , y = dt
  , by = "Point_ID"
  , all.x = T
)

mapdeck() %>%
  add_scatterplot(
    data = Map_DF, 
    lat = "Latitude",
    lon = "Longitude",
    layer_id = 'Point_ID',
    radius_min_pixels = 3,
    tooltip = "info"
    )
  )