Shiny App error after leafletProxy added

shiny
,
1

Hello all,

I have a Shiny app that uses leaflet.extras::addHeatmap() to add a layer to a leaflet map.
It works with reactive data for a date sliderInput, however, when I try an optimise it using observe(leafletProxy()) it gives me the error Warning: Error in dispatch: Invalid map parameter

  • [No stack trace available]*
#packages
require(shinyWidgets)
require(shiny)
require(tidyverse)
require(httr)
require(sf)
require(rgdal)
require(leaflet)
require(leaflet.extras)
require(maps)

#datasets
accleddata <- structure(list(event_date = structure(c(18098, 18098, 18098, 
18098, 18098, 18098), class = "Date"), latitude = c(32.3754, 
32.9243, 30.912, 30.2108, 32.4104, 35.6911), longitude = c(15.0925, 
75.1357, 75.8537, 74.9452, 61.4593, -0.6417), fatalities = c(0, 
0, 0, 0, 0, 0)), row.names = c(NA, -6L), class = c("tbl_df", 
"tbl", "data.frame"))

langs <- structure(list(Tweet.date = structure(c(1558224000, 1558224000, 
1558224000, 1558224000, 1558828800, 1558828800), class = c("POSIXct", 
"POSIXt"), tzone = "UTC"), Language = structure(c(4L, 4L, 3L, 
4L, 3L, 4L), .Label = c("#meta +lang", "ar", "en", "fr"), class = "factor"), 
    Relevant.tweets = structure(c(78L, 49L, 6L, 104L, 101L, 41L
    ), .Label = c("#indicator +num +tweets", "1", "101", "103", 
    "105", "1076", "1077", "10827", "10949", "116", "11853", 
    "12164", "12179", "12671", "13", "134", "137", "14283", "14617", 
    "15", "150", "15198", "15255", "15849", "160", "1604", "16286", 
    "16899", "170", "172", "17406", "178", "182", "18557", "196", 
    "2", "20", "204", "206", "20887", "21", "22", "23", "230", 
    "231", "2360", "24", "2428", "243", "25063", "25400", "2723", 
    "28", "28955", "29", "3", "30", "31", "31706", "3302", "33258", 
    "3378", "344", "3669", "37", "38", "3815", "388", "39", "4", 
    "4005", "403", "41", "415", "418", "4238", "426", "43", "4431", 
    "4464", "4466", "4473", "4476", "45", "46", "4712", "474", 
    "4868", "4913", "5", "50147", "5074", "5096", "52", "540", 
    "54798", "55", "55905", "561", "57", "5984", "5999", "6", 
    "60", "6091", "6137", "6192", "6289", "6323", "6393", "6687", 
    "676", "7", "70", "7058", "72", "7233", "7284", "7359", "76", 
    "7606", "7662", "7680", "7708", "78", "79", "7900", "7976", 
    "7983", "8", "8020", "803", "8102", "88", "8935", "9", "92", 
    "935", "95", "96", "9680", "98", "988"), class = "factor"), 
    group = structure(c(1L, 1L, 1L, 1L, 1L, 1L), .Label = "1", class = "factor")), row.names = c(NA, 
6L), class = "data.frame")

and the app

#app
ui <- fluidPage(
    titlePanel("Attacks Against Education - Data from AIDR and ACCLED"),
    sidebarLayout(
        sidebarPanel(top = 10, right = 5,
                     
                     sliderInput("daterange", "Select Week Starting", 
                                 as.Date(min(accleddata$event_date)), 
                                 as.Date(max(accleddata$event_date)),
                                 value = min(accleddata$event_date), 
                                 step = 7,
                                 animate = animationOptions(interval = 1000, loop = TRUE)
                     )
                     
        ), 
        mainPanel(
            leafletOutput("myheatmap"),
            br(), br(),
            
            plotOutput("plot"))
        
    )
)


# server
server <- function(input, output) {
  
##reactive statements
    
    reactive_data_chrono <- reactive({
        accleddata %>% 
        filter(event_date == input$daterange[1]) 
        })
    
    reactive_plot_data <- reactive({
        langs %>%
            filter(Tweet.date == input$daterange[1])
    })
    

#leaflet render
    output$myheatmap <- renderLeaflet({
        leaflet(height = 600) %>% 
            addProviderTiles(provider = "OpenStreetMap.HOT") %>%            
                             addHeatmap(data = accleddata, radius = 15, blur = 25)

       
        
    })
    
######the observe statement that messing up everything:

     observe(leafletProxy("myheatmap", data = reactive_data_chrono() %>%
                             clearHeatmap() %>%
                             addHeatmap(map = myheatmap, radius = 15, blur = 25)) %>%
                 fitBounds(fitBounds(lng1 = ~min(longitude), lat1 = ~min(latitude),
                                   lng2 = ~max(latitude), lat2 = ~max(latitude)))
                 
    )

    

#mybarplot   
    output$plot <- renderPlot({
        ggplot(reactive_plot_data(), aes(group, fill = Language)) + 
            geom_bar(position = "fill", width = 0.2) + 
            scale_fill_manual(values = c('#053C5E', '#25A18E', '#388697', '#388374'), 
                              labels = c('Arabic', 'English', 'French')
            ) +
            labs(title = '% Breakdown of Tweet language', x = 'Language Breakdown', y = "") + 
            coord_flip() + 
            theme(
                plot.background = element_blank(),
                panel.background = element_blank(),
                axis.text.y = element_blank(),
                axis.title.y = element_blank(),
                plot.title = element_text(family = 'Gotham', size = 18, hjust = 0.5, vjust = -5),
                legend.title = element_blank(),
                legend.position = "bottom",
                legend.spacing.x = unit(0.2, 'cm'),
                #axis.title.x = element_blank(),
                axis.text.x = element_text(size = 16, family = 'Gotham')
                
            ) + guides(fill = guide_legend(reverse = TRUE))
        

       
    }, height = 200)
    
    

    
    
    
    
    
    
    
}


# Run that thang
shinyApp(ui = ui, server = server)

I'd be very grateful for any help, thank you.

2

Hi,

Thanks for making a nice Reprex, but unfortunately you missed one dataset aidr_map_data which leads to an app crash. Could you add this to your datasets?

Thanks
PJ

3

Hi PJ,

thank you very much and apologies for the missed data.

I just took the code dependant on that data, out of the shiny app as it wasnt necessary.

the problem is only when the observe(leafletProxy() argument is added - commented out - it works.

Thanks so much for your help with this.

Elliot

4

Hi,

The error was due to the fact that you had the wrong variable myheatmap in addHeatmap and furthermore an incorrect use of double fitBounds plus mistake in latitude where longitude should be.

This is my fix:

observe({
    leafletProxy("myheatmap", session, data = reactive_data_chrono()) %>%
      clearHeatmap() %>%
      addHeatmap(radius = 15, blur = 25) %>% 
      fitBounds(lng1 = ~min(longitude), lat1 = ~min(latitude),
                lng2 = ~max(longitude), lat2 = ~max(latitude))

  })

Le me know if this works,

PJ

1 Like
5

PJ - not sure how I can buy you a beer for this one, but thank you nonetheless - awesome.

1 Like
6

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