inst/examples/us_census/server.R

In saurfang/shinyCartogram: Cartogram map component for Shiny, using d3-cartogram

shinyServer(function(input, output, session) {

  #Create cartogram object and pass base dataset and column definition
  map <- createCartogram(session, "cartogram")
  session$onFlushed(once = TRUE, function() {
    map$setData(rename(nst2013, name = NAME))
    map$setColumns(select(columns, title = name, name = key, format))
  })

  #Update dataset
  observe({
    set.seed(1138)
    map$setData(rename(nst2013, name = NAME) %>% sample_frac(input$frac))
  })

  #Update scale variable
  observe({
    map$scaleBy(filter(columns, name == input$scaleBy, years == input$year)$key)
  })

  #Update color variable
  observe({
    map$colorBy(filter(columns, name == input$colorBy, years == input$year)$key)
  })

  #Update choices based on year selected
  observe({
    choices <- filter(columns, is.na(years) | years == input$year)$name

    update <- function(val) {
      value <- intersect(isolate(input[[val]]), choices)
      updateSelectInput(session, val, NULL, choices, if(length(value) == 1) value)
    }

    update("scaleBy")
    update("colorBy")
  })
})