Delete map after pressing reset button on shiny - r

Question

I am not able to delete the generated map after I press the reset button on shiny, could you help me to insert the code to delete the map made after pressing the button? For both selectInput works normally, only the map that is not deleted from the screen.
library(shiny)
library(shinythemes)
library(lubridate)
library(googleway)
set_key("API KEY")
df1<- structure(
list(
Marketname = c("Market1","Market1", "Market2","Market2", "Market3", "Market3", "Market4", "Market4"),
Latitude = c(-22.900200453490385, -22.900200453490385,-22.89279876292728,-22.89279876292728,-22.89107669207457,-22.89107669207457,-22.91668421655409,-22.91668421655409),
Longitude = c(-48.448779371935494,-48.448779371935494, -48.45043377250408,-48.45043377250408,-48.44108027972275,-48.44108027972275,-48.43786997555729,-48.43786997555729)),
row.names = c(NA, 8L), class = "data.frame")
ui <- fluidPage(
shiny::navbarPage(theme = shinytheme("flatly"), collapsible = TRUE,
br(),
tabPanel("Rota",
sidebarLayout(
sidebarPanel(
selectizeInput("market1", label = h5("Choose starting point:"), choices = NULL,
multiple = TRUE,
options = list(maxItems = 1)),
selectizeInput("market2", label = h5("Choose destination point:"), choices = NULL,
multiple = TRUE,
options = list(maxItems = 1)),
actionButton(inputId = "getRoute", label = "Get route"),
actionButton(inputId = "reset", label = "Reset")),
mainPanel(
tabsetPanel(
tabPanel("Route",google_mapOutput(outputId = "mapWarsaw"),
)
))
))))
server <- function(input, output,session) {
observe({
updateSelectizeInput(session, "market1",
choices = unique(df1$Marketname)
)
})
observe({
excludeOption <- NULL
if (!is.null(input$market1)) {
excludeOption <- input$market1
}
updateSelectizeInput(session, "market2",
choices = unique(df1$Marketname[df1$Marketname != excludeOption])
)
})
observeEvent(input$getRoute, {
origin <- df1[df1$Marketname == input$market1, c("Latitude", "Longitude")][1, ]
destination <- df1[df1$Marketname == input$market2, c("Latitude", "Longitude")][1, ]
route <- google_directions(origin = origin,
destination = destination,
mode = "driving")
df_routes <- data.frame(polyline = direction_polyline(route))
df_way <- cbind(
route$routes$legs[[1]]$end_location,
data.frame(address = route$routes$legs[[1]]$end_address)
)
m3<-google_map() %>%
add_polylines(data = df_routes, polyline = "polyline", stroke_weight = 4)
output$mapWarsaw <- renderGoogle_map({
m3
})
})
observeEvent(input$reset, {
updateSelectInput(session, "market1", selected = "")
updateSelectInput(session, "market2", selected = "")
})
}
shinyApp(ui = ui, server = server)
Here I pressed reset, the selectInput was cleared, but the map was not, so I would like to insert some code that cleared the screen. Of course, after inserting the selectInput options again, the map was generated normally on the screen.

Answer 1

I recommend using a reactiveVal to store whether you want to plot or not, then req(.) that value in your plot.
A simple example:
library(shiny)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
numericInput("n", "N", value = 2),
actionButton("toggle", "Toggle")
),
mainPanel(
plotOutput("plot")
)
)
)
server <- function(input, output, session) {
doplot <- reactiveVal(TRUE)
observeEvent(input$toggle, {
doplot(!isTRUE(doplot()))
})
output$plot <- renderPlot({
req(doplot())
plot(runif(input$n))
})
}
shinyApp(ui, server)
doplot defaults to TRUE, so it starts plotting immediately (assuming input$n has a value), and every time input$n is changed, a new plot is rendered;
when you click on toggle, the doplot is inverted, and the dependent output$plot will "fail" the req(doplot()) requirement and clear the plot;
this could be improved to give a clearer indication that the empty plot is because the user toggled the button ... in this case, I should likely change the style of the button to clearly indicate the state, but that's aesthetics and may or may not apply to your app
Another similar method would be to store the data in a reactiveVal, and require it, perhaps like this:
library(shiny)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
numericInput("n", "N", value = 2),
actionButton("toggle", "Toggle")
),
mainPanel(
plotOutput("plot")
)
)
)
server <- function(input, output, session) {
mydat <- reactiveVal(NULL)
observeEvent(input$toggle, {
req(input$n)
if (is.null(mydat())) {
mydat(runif(input$n))
} else mydat(NULL)
})
output$plot <- renderPlot({
plot(req(mydat()))
})
}
shinyApp(ui, server)
This second method won't work as well if you need to preserve the data.