CODEWITHSUNDEEP
rshinyr-leaflet
cdeterman
cdeterman

Reputation: 19960

Auto Zoom Updated leafletProxy Map object

I am experimenting with the leaflet package for some maps in Shiny. I would like to be able to have a base map that data will change and subsequently be remapped. However, I am trying to use the leafletProxy function whereby there is a base map and I just change the data points that are added. All of this works however the map doesn't zoom to the datapoints location. It remains at the farthest zoom.

enter image description here

The code to reproduce the problem:

library(shiny)
library(leaflet)

r_colors <- rgb(t(col2rgb(colors()) / 255))
names(r_colors) <- colors()

ui <- fluidPage(
  leafletOutput("mymap"),
  p(),
  actionButton("goButton", "New Points")
)

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

  output$mymap <- renderLeaflet({
    leaflet() %>%
      addProviderTiles("Stamen.TonerLite",
                       options = providerTileOptions(noWrap = TRUE)
      )
  })

  observeEvent(input$goButton, {
    points <- cbind(rnorm(40) * 2 + 13, rnorm(40) + 48)

    leafletProxy('mymap', session) %>%
      clearMarkers() %>%
      addMarkers(data = points)
  })
}

shinyApp(ui, server)

I would like the map to automatically zoom in once new points have been added.

Upvotes: 3

Views: 2612

Answers (2)

dca
dca

Reputation: 652

I revised G. Cocca's answer (mostly by adding a dataframe of "points") to get this:

library(shiny)
library(leaflet)

r_colors <- rgb(t(col2rgb(colors()) / 255))
names(r_colors) <- colors()

ui <- fluidPage(
  leafletOutput("mymap"),
  p(),
  actionButton("goButton", "New Points")
)

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

  output$mymap <- renderLeaflet({
    leaflet() %>%
      addProviderTiles("Stamen.TonerLite",
                       options = providerTileOptions(noWrap = TRUE)
      )
  })

  observeEvent(input$goButton, {
    points <- data.frame("long" = rnorm(40) * 2 + 13, 
                            "lat" = rnorm(40) + 48)


    leafletProxy('mymap', session) %>%
      clearMarkers() %>%
      addMarkers(data = points) %>%
      fitBounds(lng1 = max(points$long),lat1 = max(points$lat),
                lng2 = min(points$long),lat2 = min(points$lat))


  })
}

shinyApp(ui, server)

Upvotes: 1

G. Cocca
G. Cocca

Reputation: 2541

try to add argument "fitBounds" in leafletProxy()

leafletProxy('mymap', session) %>%
  clearMarkers() %>%
  addMarkers(data = points) %>%
  fitBounds(lng1 = max(points$long),lat1 = max(points$lat),
            lng2 = min(points$long),lat2 = min(points$lat))

Upvotes: 5

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