How can i use the leaflet add control inputs in the shiny R app?

user_13917839 0
Viewed 225

I want to make a map using leaflet in shiny with a checkboxGroupInput inside the map and use the inputs of the checkboxGroupInput to update the data that is used to make the map. But I don't know how to use those inputs, I tried the code below but it didn't work. I would aprecciate any advice.

library(shiny)
library(leaflet)


df <- data.frame(
  cat = sample(letters[1:3],10, replace = TRUE),
  long = runif(10,60,100),
  lat  = runif(10,40,60)
)

ui <- fluidPage(
  
  leafletOutput("map1")
  
)

server <- function(input, output, session) {
  
  output$map1 <- renderLeaflet({
    
    leaflet(df %>% filter(cat %in% input$x))%>%
      addTiles() %>%
      addMarkers(~long,~lat) %>%
      addControl(checkboxGroupInput(inputId = 'x',
                                    'Select cat',
                                    unique(df$cat)))
  })
  
}

shinyApp(ui, server)
leaflet shiny r
1 Answers

I think it is simpler to use a layer control using addLayersControl. You only need to set the group parameter of addMarkers with the column cat of your data frame. Finally, set the parameter overlayGroups of addLayersControl with the unique values of column cat.

library(shiny)
library(leaflet)

df <- data.frame(
  cat = sample(letters[1:3],10, replace = TRUE),
  long = runif(10,60,100),
  lat  = runif(10,40,60)
)

ui <- fluidPage(  
  leafletOutput("map1")
)

server <- function(input, output, session) {
  output$map1 <- renderLeaflet({
    leaflet(df)%>%
      addTiles() %>%
      addMarkers(~long, ~lat, group = ~cat) %>%
      addLayersControl(
        overlayGroups = unique(df$cat),
        options = layersControlOptions(collapsed = FALSE)
      )
  })
}

shinyApp(ui, server)

Using different icons per group

As is in R Leaflet documentation, there are many possible ways to have custom icons. Below is one of them for your code. Please note that you need to provide an icon for all possible categories.

library(shiny)
library(leaflet)

df <- data.frame(
  cat = sample(letters[1:3],10, replace = TRUE),
  long = runif(10,60,100),
  lat  = runif(10,40,60)
)

leafIcons <- icons(
  iconUrl = sapply(df$cat, function(x) switch (x, 
            "a" = "https://leafletjs.com/examples/custom-icons/leaf-green.png",
            "b" = "https://leafletjs.com/examples/custom-icons/leaf-red.png",
            "c" = "https://leafletjs.com/examples/custom-icons/leaf-orange.png"
  )),
  iconWidth = 38, iconHeight = 95,
  iconAnchorX = 22, iconAnchorY = 94,
  shadowUrl = "https://leafletjs.com/examples/custom-icons/leaf-shadow.png",
  shadowWidth = 50, shadowHeight = 64,
  shadowAnchorX = 4, shadowAnchorY = 62
)

ui <- fluidPage(
  leafletOutput("map1")
)

server <- function(input, output, session) {
  output$map1 <- renderLeaflet({
    leaflet(df)%>%
      addTiles() %>%
      addMarkers(~long, ~lat, group = ~cat, icon = leafIcons) %>%
      addLayersControl(
        overlayGroups = unique(df$cat),
        options = layersControlOptions(collapsed = FALSE)
      )
  })
}

shinyApp(ui, server)
user_43223180
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