Making selectizeInput reactive to show/hide markers

Question

I am in the process of making a map of street food in Oaxaca, Mexico, although I am running into some trouble. I am trying to produce a leaflet map in Shiny and understand the UI side of shiny, although the server side not as much. I understand that I have to add either observe() or reactive() to the server side to produce the desired results, but I cannot seem to get it to work. I included addlayercontrol() to the leaflet as this effect is desired (hide and show markers based on what is selected) although I would like the selectizeImput to control the layers. Below is my code, I included a small subset of the dataset, as well as some commented out code of what I tried on the server side.

library(leaflet)
library(shiny)
library(shinydashboard)
library(dplyr)

#Data Sample

long <- c(-96.72363, -96.72880, -96.72700)
lat <- c(17.06167, 17.06200, 17.06170 )
name <- c("jim", "grant", "pablo")
food <- c("tacos", "burger", "elote")


df <- data.frame(long, lat, name, food)

#subsets

palette<- colorFactor(palette = c("blue", "green", "black"),
                      domain = df$food)
tacos <- dplyr::filter(df, grepl("tacos", food))

burger <- dplyr::filter(df, grepl("burger", food))

elote <- dplyr::filter(df, grepl("elote", food))


#ui 


ui <-fluidPage(
  titlePanel(title = "Street Food Oaxaca"),
  sidebarLayout(
    sidebarPanel(
      selectizeInput("food","Select a Type:",
                  choices = unique(df$food),
                  selected = ,
                  multiple = TRUE)),
    mainPanel(h3("Map"), leafletOutput("m", width = "800", height = "600"))
  )
)

#server
server <- function(input, output, session){ 
    output$m = renderLeaflet({
    leaflet(data = df) %>%
      setView(lng = -96.725, lat = 17.0618, zoom =14)%>%
      addTiles() %>%
      addCircleMarkers( layerId = tacos,
                          data = tacos,
                          ~long,
                          ~lat,
                          group = 'tacos',
                          popup = ~as.character(name),
                          radius = 2,
                          color =  ~palette(food),
                          fillOpacity = 0.5) %>%
        addCircleMarkers( layerId = burger,
                          data = burger,
                          ~long,
                          ~lat,
                          group = 'burger',
                          popup = ~as.character(name),
                          radius = 2,
                          color =  ~palette(food),
                          fillOpacity = 0.5) %>%
        addCircleMarkers( layerId = elote,
                          data = elote,
                          ~long,
                          ~lat,
                          group = 'elote',
                          popup = ~as.character(name),
                          radius = 2,
                          color =  ~palette(food),
                          fillOpacity = 0.5) %>%
        # addPolygons(data = poly,
        #           ~long,
        #           ~lat,
        #           weight = 3,
        #           color = "red",
        #           group = "Restricted Zone" ,
        #           popup = "Restricted Zone")
      addLayersControl(
        overlayGroups = c("tacos","burger","elote", "Restricted Zone"),
        options = layersControlOptions(collapsed = TRUE)
      )


    })
}    
      
      
      #  observeEvent(
      # if(function(input$food, value ="tacos"))
      #   output$m = renderLeaflet('m')%>%
      #    removeMarker(layerId = m,c('burger', 'elote')))
                               
      #removeMarker(group == C('two', 'three'))

      # data_f <- reactive({
      #   dplyr::filter(df$food == "tacos")
      # })
      # 
      # observeEvent(data_f, {
      # 
      #   leafletProxy("map") %>%
      # 
      #     clearMarkers() }) 
    
         

  


 #Run the application 
shinyApp(ui = ui , server = server)

Answer 1

Try this

library(leaflet)
library(shiny)
library(shinydashboard)
library(dplyr)

#Data Sample

long <- c(-96.72363, -96.72880, -96.72700)
lat <- c(17.06167, 17.06200, 17.06170 )
name <- c("jim", "grant", "pablo")
food <- c("tacos", "burger", "elote")


df <- data.frame(long, lat, name, food)

#subsets

palette <- colorFactor(palette = c("blue", "green", "black"),
                      domain = df$food)
tacos <- dplyr::filter(df, grepl("tacos", food))

burger <- dplyr::filter(df, grepl("burger", food))

elote <- dplyr::filter(df, grepl("elote", food))

ui <-fluidPage(
  titlePanel(title = "Street Food Oaxaca"),
  sidebarLayout(
    sidebarPanel(
      selectizeInput("food","Select a Type:",
                     choices = unique(df$food),
                     selected = food[1],
                     multiple = TRUE)),
    mainPanel(h3("Map"), leafletOutput("m", width = "800", height = "600"))
  )
)

#server
server <- function(input, output, session){ 
  
  df1 <- eventReactive(input$food, {
    df %>% dplyr::filter(food %in% input$food)
  })
  
  output$m = renderLeaflet({
    leaflet(data = df1()) %>%
      setView(lng = -96.725, lat = 17.0618, zoom =14)%>%
      addTiles() %>%
      addCircleMarkers( # layerId = input$food,
                        # data = input$food,
                        ~long,
                        ~lat,
                        #group = input$food,
                        #popup = ~as.character(name),
                        radius = 2,
                        color =  ~palette(input$food),
                        fillOpacity = 0.5) %>%
      # addCircleMarkers( layerId = burger,
      #                   data = burger,
      #                   ~long,
      #                   ~lat,
      #                   group = 'burger',
      #                   popup = ~as.character(name),
      #                   radius = 2,
      #                   color =  ~palette(food),
      #                   fillOpacity = 0.5) %>%
      # addCircleMarkers( layerId = elote,
      #                   data = elote,
      #                   ~long,
      #                   ~lat,
      #                   group = 'elote',
      #                   popup = ~as.character(name),
      #                   radius = 2,
      #                   color =  ~palette(food),
      #                   fillOpacity = 0.5) %>%
      # addPolygons(data = poly,
      #           ~long,
      #           ~lat,
      #           weight = 3,
      #           color = "red",
      #           group = "Restricted Zone" ,
      #           popup = "Restricted Zone")
      addLayersControl(
        overlayGroups = c("tacos","burger","elote", "Restricted Zone"),
        options = layersControlOptions(collapsed = TRUE)
      )
    
    
  })
}    

#Run the application 
shinyApp(ui = ui , server = server)