Shiny Leaflet map renders twice on switching input - r

Question

I'm trying to produce a Shiny app with Leaflet that renders a choropleth map based on different input criteria. The map displays incidents of different types (input$type) and backgrounds (input$background). When additional types or backgrounds are specified, polygons are filled with updated incident data. It is working correctly with one snag. When I switch the date input from date range (input$dateInput) to presidential period (input$president), the choropleth for presidential period renders once, displaying polygons with no data, and then again with the polygons filled with the correct data for the pre-selected period ("President1"). How do I avoid the map rendering twice like this when the Presidency tab is pressed?
Question also listed here on RStudio Community.
The raw data and shapefile used can be accessed here: https://github.com/cjbarrie/shiny_egy.
Working example:
Name of raw data: wikiraw
Name of shapefile: shapefile
Global:
library(shiny)
library(shinydashboard)
library(shinythemes)
library(leaflet)
library(rgdal)
library(rmapshaper)
library(sp)
library(dplyr)
library(lubridate)
wikiraw <-read.csv("~/wikisample_SO.csv")
shapefile <- readOGR("~/EGY_adm2.shp")
shapefile<-spTransform(shapefile, CRS("+init=epsg:4326"))
## Simplify shapefile to speed up rendering
shapefile <- ms_simplify(shapefile, keep = 0.01, keep_shapes = TRUE)
wikbounds<-bbox(shapefile)
wikiraw$incident_date <- as.Date(wikiraw$incident_date,
format = "%m/%d/%Y")
wikiraw$presidency <- rep(NA, nrow(wikiraw))
wikiraw$incident_date1 <- as.numeric(wikiraw$incident_date)
wikiraw$event <- rep(1,nrow(wikiraw))
## Generate presidency categorical var.
wikiraw$presidency <- cut(wikiraw$incident_date1,
breaks = c(-Inf, 15016, 15521, 15889, 16229, Inf),
labels = c("President1", "President2", "President3", "President4", "President5"),
right = FALSE)
Snippet of data.frame wikiraw:
ID_2 incident_date incident_background incident_type presidency event
1 168 2013-11-26 Cultural Group President4 1
2 133 2013-11-29 Cultural Group President4 1
3 137 2014-01-25 Cultural Group President4 1
4 168 2011-01-28 Cultural Collective President1 1
5 168 2016-04-25 Cultural Group President5 1
6 163 2015-02-08 Political Individual President5 1
UI:
ui <- dashboardPage(
dashboardHeader(title = "Map tool"),
dashboardSidebar(sidebarMenu(menuItem("Map", tabName = "map"),
selectInput("input_type", "Date input type",
c("Date", "Presidency")),
uiOutput("dateSelect"),
uiOutput("typeSelect"),
uiOutput("backgroundSelect"),
uiOutput("presidentSelect"))),
dashboardBody(tabItems(
tabItem(tabName = "map",
leafletOutput("mymap", height=500)))))
Server:
server <- function(input, output, session) {
output$dateSelect <- renderUI({
switch(input$input_type,
"Date" = dateRangeInput("dateInput", "Dates:",
min=min(wikiraw$incident_date), max = max(wikiraw$incident_date),
start = min(wikiraw$incident_date), end = max(wikiraw$incident_date)),
"Presidency" = checkboxGroupInput("president", "Presidency",
choices = levels(wikiraw$presidency),
selected = "President1"))
})
output$typeSelect <- renderUI({
selectInput("type", "Incident type",
choices = unique(wikiraw$incident_type), multiple = TRUE,
selected = wikiraw$incident_type[1])})
output$backgroundSelect <- renderUI({
checkboxGroupInput("background", "Incident background",
choices = unique(wikiraw$incident_background),
selected = wikiraw$incident_background[1])})
selected <- reactive({
wikiagg <- wikiraw %>% group_by(ID_2, incident_date, incident_type, incident_background, presidency) %>%
summarize(sum_event = sum(event))
if(input$input_type=="Date"){wikiagg <- filter(wikiagg,
incident_date >= min(input$dateInput),
incident_date <= max(input$dateInput),
incident_type%in%input$type,
incident_background%in%input$background)}
if(input$input_type=="Presidency"){wikiagg <- filter(wikiagg,
incident_type%in%input$type,
incident_background%in%input$background,
presidency%in%input$president)}
wikiagg <- wikiagg %>% group_by(ID_2) %>%
summarize(sum_event = sum(sum_event))
wikiagg
})
output$mymap <- renderLeaflet({
leaflet() %>%
addTiles() %>%
setView(mean(wikbounds[1,]),
mean(wikbounds[2,]),
zoom=6
)
})
observe({
if(!is.null(input$dateInput)){
shapefile#data <- left_join(shapefile#data, selected(), by="ID_2")
##Define palette across range of data
wikiaggpal <- wikiraw %>% group_by(ID_2) %>%
summarize(sum_event = sum(event))
pal <- colorBin("YlOrRd", wikiaggpal$sum_event, bins=5, na.color = "#bdbdbd")
leafletProxy("mymap", data = shapefile) %>%
addTiles() %>%
clearShapes() %>%
addPolygons(data = shapefile, fillColor = ~pal(sum_event), fillOpacity = 0.7,
color = "white", weight = 2)
}})
}
shinyApp(ui, server)
Gif of issue:
https://imgur.com/a/FnfOGKi
Any help would be hugely appreciated!

Answer 1

What if you change the reactive to a reactiveValue and assign the data in an observe? I don't know if it is working correctly as I dont know which shapes & colors to expect, but I am not seeing that double rendering anymore.
(Data & Preparation from question is used)
library(shiny)
library(shinydashboard)
library(shinythemes)
library(leaflet)
library(rgdal)
library(rmapshaper)
library(sp)
library(dplyr)
library(lubridate)
ui <- dashboardPage(
dashboardHeader(title = "Map tool"),
dashboardSidebar(sidebarMenu(menuItem("Map", tabName = "map"),
selectInput("input_type", "Date input type",
c("Date", "Presidency")),
uiOutput("dateSelect"),
uiOutput("typeSelect"),
uiOutput("backgroundSelect"),
uiOutput("presidentSelect"))),
dashboardBody(tabItems(
tabItem(tabName = "map",
leafletOutput("mymap", height=500)))))
server <- function(input, output, session) {
output$dateSelect <- renderUI({
switch(input$input_type,
"Date" = dateRangeInput("dateInput", "Dates:",
min=min(wikiraw$incident_date), max = max(wikiraw$incident_date),
start = min(wikiraw$incident_date), end = max(wikiraw$incident_date)),
"Presidency" = checkboxGroupInput("president", "Presidency",
choices = levels(wikiraw$presidency),
selected = "President1"))
})
output$typeSelect <- renderUI({
selectInput("type", "Incident type",
choices = unique(wikiraw$incident_type), multiple = TRUE,
selected = wikiraw$incident_type[1])})
output$backgroundSelect <- renderUI({
checkboxGroupInput("background", "Incident background",
choices = unique(wikiraw$incident_background),
selected = wikiraw$incident_background[1])})
sel_reactval = reactiveValues(s = NULL)
# selected <- reactive({
observe({
wikiagg <- wikiraw %>% group_by(ID_2, incident_date, incident_type, incident_background, presidency) %>%
summarize(sum_event = sum(event))
if(input$input_type=="Date"){wikiagg <- filter(wikiagg,
incident_date >= min(input$dateInput),
incident_date <= max(input$dateInput),
incident_type%in%input$type,
incident_background%in%input$background)}
if(input$input_type=="Presidency"){wikiagg <- filter(wikiagg,
incident_type%in%input$type,
incident_background%in%input$background,
presidency%in%input$president)}
wikiagg <- wikiagg %>% group_by(ID_2) %>%
summarize(sum_event = sum(sum_event))
sel_reactval$s = wikiagg
# wikiagg
})
output$mymap <- renderLeaflet({
leaflet() %>%
addTiles() %>%
setView(mean(wikbounds[1,]),
mean(wikbounds[2,]),
zoom=6
)
})
observe({
req(!is.null(input$dateInput))
req(nrow(as.data.frame(sel_reactval$s))!=0)
# if(!is.null(input$dateInput)){
# shapefile#data <- left_join(shapefile#data, selected(), by="ID_2")
shapefile#data <- left_join(shapefile#data, sel_reactval$s, by="ID_2")
##Define palette across range of data
wikiaggpal <- wikiraw %>% group_by(ID_2) %>%
summarize(sum_event = sum(event))
pal <- colorBin("YlOrRd", wikiaggpal$sum_event, bins=5, na.color = "#bdbdbd")
leafletProxy("mymap") %>%
addTiles() %>%
clearShapes() %>%
addPolygons(data = shapefile, fillColor = ~pal(sum_event), fillOpacity = 1,
color = "white", weight = 2)
# }
})
}
shinyApp(ui, server)