popupGraph - R, Leaflet: Why are my popup graphs blank?

Question

Mapping in R - Shiny, leaflet.

Been trying to figure out how to display my line plots (library - ggplot2) as popups in my map. Primarily, I'm using popupGraph (leafpop) to do this. Basically want to display line graphs where x is time, and y is new covid cases. When the user clicks on a county, the popup should only display a graph for the plot of that county clicked.

The popups work, but they're blank, they don't show my graphs. Not sure what I'm doing wrong. I've been looking through other stackOverflow problems to help me solve mine (primarily: Control the size of popupGraph() from leaflet in r shiny, R Leaflet PopupGraph - addPopupGraphs on map_marker_click) But I'm drawing a blank, and there doesn't seem to be a lot of online resources for this function. Any suggestions or ideas on why my graphs aren't plotting? I can't tell if it's a simple syntax problem, or if I'm approaching the function completely wrong.

Here's my data for variables for US counties, "counties1" and covid-19 cases in those counties, "df": (Edited for replicability -- Autauga County in Alabama sample)

##* COVID-19 DATA:
 head(df)
    FIPS     Admin2 Province_State      Lat     Long_        date value
637 1001 Autauga-AL             AL 32.53953 -86.64408  2020-01-22     0
638 1001 Autauga-AL             AL 32.53953 -86.64408  2020-01-23     1
639 1001 Autauga-AL             AL 32.53953 -86.64408  2020-01-24     2
640 1001 Autauga-AL             AL 32.53953 -86.64408  2020-01-25     3
641 1001 Autauga-AL             AL 32.53953 -86.64408  2020-01-26     4
642 1001 Autauga-AL             AL 32.53953 -86.64408  2020-01-27     5
> 

dput(head(df))
structure(list(
FIPS = c(1001L, 1001L, 1001L, 1001L, 1001L, 1001L), 
Admin2 = c("Autauga-AL", "Autauga-AL", "Autauga-AL", "Autauga-AL", "Autauga-AL", "Autauga-AL"), 
Province_State = c("AL", "AL", "AL", "AL", "AL", "AL"), 
Lat = c(32.53952745, 32.53952745, 32.53952745, 
32.53952745, 32.53952745, 32.53952745), 
Long_ = c(-86.64408227,  -86.64408227, -86.64408227, -86.64408227, -86.64408227, -86.64408227), 
date = structure(c(18283, 18284, 18285, 18286, 18287, 18288), class = "Date"), 
value = c(0, 1, 2, 3, 4, 5)), 
row.names = 637:642, class = "data.frame")

###COUNTY (polygons) DATA:
> head(counties1)

  STATEFP COUNTYFP GEOID         NAME          ALAND   AWATER    INTPTLAT
1      01     001 01001    Autauga-AL          1539614693 25744269 +32.5322367

      INTPTLON STATE_NAME 
0 -086.6464395         AL


> dput(head(counties1))
structure(list(
STATEFP = c("01"), 
COUNTYFP = c("001"), 
GEOID = c("01001"), 
NAME = c("Autauga-AL"), 
ALAND = c("1539614693"), 
AWATER = c(""25744269""), 
INTPTLAT = c("+32.5322367"), 
INTPTLON = c("-086.6464395"), 
STATE_NAME = c("AL"),  
row.names = 0:1, class = "data.frame")

Here's my UI:

library(shiny)
library(shinydashboard)
library(leafpop)
library(sf)
library(tidyverse)

ui <- dashboardPage(
    dashboardHeader(),
    dashboardSidebar(),
    dashboardBody(leafletOutput("map"),
    )

Here's my server, I think my problem is with the function called "subset_county". I've commented on it to show what I think I'm trying to accomplish in it. Sorry, I've only been using R Shiny for a few months and haven't yet fully grasped how to create reactive functions:

server <- function(session, input, output) 
  
###   subset counties based on click event, maybe?
     subset_county <- reactive({
      click_it <- input$map_shape_click  ##click on county polygon to create reactive click function...
           data <- df[df$Admin2 == click_it$NAME,]     ## … where data from df is pulled - when the column for df$Admin2 is the same as the name of the clicked polygon (*Thanks @akrun for the edit on brackets over parentheses.)
    
       ggplot(data= data(), 
                      aes(x= date, y = value)) + geom_line()
    })


##### or should the plot be rendered outside the subset_county function, in renderPlot()?
  #  output$plot <-renderPlot(
  # plot <-   ggplot(data= subset_county(), 
   #                aes(x= date, y = value)) + geom_line()
  # )


    

############ DISPLAY MAP  
   output$map <- renderLeaflet({
     
     leaflet() %>%
       addProviderTiles(providers$CartoDB.DarkMatter) %>%
       addPolygons(data=counties,  
                   color = "black", 
                   weight = 0.1,
                   opacity = 1.0, 
                   fillOpacity = 0.15, 
                   fillColor = "transparent",
                   group= "counties",
                   popup = popupGraph(subset_county),
                   layerId = ~counties1$GEOID
       ) %>% 
       addLayersControl( baseGroups = c("CartoDB.DarkMatter"),
                         overlayGroups = c("counties"),
   })

      
}
########################################################################################
shinyApp(ui = ui, server = server)

I hope my data is presentable enough! Any suggestions or resources for how I can solve my popupGraph issue?

Q007 Q007 · Accepted Answer · 2020-06-29T00:33:40

There are couple of things, your selected data, i.e. subset_county is a reactive item, it will only acquire data based on how and when a user selects using the UI. In your case when you are referencing this to plot the graph you may want to use, subset_county(). The other thing I noticed is that in the leaflet call you have data=counties, infact it should be data = subset_county() because you only want the graph for your selected items. You may need to use an observer as I think you are trying to display graph of a county only its selected.

Refer to https://rstudio.github.io/leaflet/shiny.html for a very intro on shiny and leaflet

popupGraph - R, Leaflet: Why are my popup graphs blank?

1 Answers