R shiny: deselect from selectize

Question

First of all, my thanks to Shree, who cleaned and made my previous code more performant here

Anyhow, I have some code that enables a user to select one or more species (from selectizeInput). The application shows you the species distribution on the map.

Now, I am puzzled, because I cannot deselect species? Once distributions are plotted, they remain on the map and I cannot remove them anymore... I have been looking thoroughly, but unable to see it.. I am pretty new to shiny.. so probably an easy mistake?

All code below, THanks!!! JOnas

DATAFRAME

df<- data.frame(
  Number_Total = sample(c("5", "6", "1", "3")),
  Species = sample(c("Ilione trifaria", "Pherbellia argyrotarsis", 
"Euthycera seguyi", "Ilione trifaria")),
  X= sample(c("37", "28", "21", "30")),
  Y= sample(c("-5", "-16", "-10", "-15"))
)

UI

ui <- (fluidPage(titlePanel("Species Checker"),  
                 sidebarLayout(
                   sidebarPanel(
                      selectizeInput('species', 'Choose species', 
choices = df$Species, multiple = TRUE, 
options = list(placeholder = 'select species'))
                     ),
                   mainPanel(
                     leafletOutput("CountryMap", width = 600, height = 600))
                 )
))

SERVER

server <- function(input, output, session) {
  map_data <- reactive({
    #req(input$species)
    df[df$Species %in% input$species, ]
  })

  output$CountryMap <- renderLeaflet({
    leaflet() %>% addTiles() %>% 
      setView(lng = 20, lat = 40, zoom = 2)
  })

  map_proxy <- leafletProxy("CountryMap")

  observe({
    md <- map_data()
    map_proxy %>%
      addCircles(lng = md$Y, lat = md$X, weight = 10, 
                 radius = sqrt(md$Number_Total)*15000, popup = md$Species)
  })
}

Run the application

shinyApp(ui = ui, server = server)

Answer 1

Try the below (I've unquoted some of the variables in df as otherwise the app crashes):

library(tidyverse)
library(shiny)
library(leaflet)

df <- data.frame(
  Number_Total = sample(c(5, 6, 1, 3)),
  Species = sample(c("Ilione trifaria", "Pherbellia argyrotarsis", 
                     "Euthycera seguyi", "Ilione trifaria")),
  X= sample(c(37, 28, 21, 30)),
  Y= sample(c(-5, -16, -10, -15))
)

ui <- (fluidPage(titlePanel("Species Checker"),  
                 sidebarLayout(
                   sidebarPanel(
                     selectizeInput('species', 'Choose species', 
                                    choices = df$Species, multiple = TRUE, 
                                    options = list(placeholder = 'select species'))
                   ),
                   mainPanel(
                     leafletOutput("CountryMap", width = 600, height = 600))
                 )
))

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

  map_data <- reactive({
    #req(input$species)
    df[df$Species %in% input$species, ]
  })

  output$CountryMap <- renderLeaflet({

    leaflet() %>% addTiles() %>% 
      setView(lng = 20, lat = 40, zoom = 2) %>%
      addCircles(lng = map_data() %>% pull(Y), lat = map_data() %>% pull(X), weight = 10, 
                 radius = sqrt(map_data() %>% pull(Number_Total))*15000, 
                 popup = map_data() %>% pull(Species))

    })

}

shinyApp(ui = ui, server = server)

You need to pull the values directly from the reactive context; I'd also suggest to do this in one statement rather than spreading it around.

PS In case your initial dataframe actually does contain all the variables in character format, you can add just in case the mutate_at statement in map_data part, like this:

map_data <- reactive({
    #req(input$species)
    df[df$Species %in% input$species, ] %>%
      mutate_at(vars(c("Number_Total", "X", "Y")), funs(as.numeric))

Then the script functions also with your initial dataframe provided here without manual changes.