possible to implement two sequential flyTo in leaflet R - r

Question

I would like to create a Leaflet Map which renders at a default location, at a zoom level of 4, and then when the user clicks the go button, pans from location to another, both of which have been selected from a dropdown.
I've tried using the following code, the data for which can be found # https://github.com/eoefelein/COVID_Business_Recovery_and_Social_Capital/tree/master/socialCapitalEmployment/data
library(sf)
library(tigris)
library(shiny)
library(shinydashboard)
library(tidyverse)
library(leaflet)
# data loading and processing
USA <- st_read(dsn = 'data/cb_2018_us_county_5m.shp')
counties_sf <- st_as_sf(USA)
counties_reproject_sf <- st_transform(counties_sf, 4326) %>% filter(COUNTYFP < 60010)
emp_rate <- read_csv('data/synthetic_emp_rate_pred.csv')
emp_rate$countyfips <- sprintf("%05d", emp_rate$countyfips)
states_sf_coef <- geo_join(counties_reproject_sf, emp_rate, "GEOID", "countyfips", how='inner')
ui <- fluidPage(
dashboardPage(
dashboardHeader(title="Employee Rate Data"),
dashboardSidebar(
sidebarMenu(
menuItem(
"Maps",
tabName = "maps",
icon=icon("globe")
)
)
),
dashboardBody(
tabItems(
tabItem(
tabName = "maps",
tags$style(type="text/css","#all_airports {height:calc(100vh - 80px) !important;}"),
fluidRow(column(4),
column(8,
selectInput(inputId = "FromCounty",
label="from",
choices=c(unique(emp_rate$countyname)),
selected = 'Travis County, Texas'
),
selectInput(inputId = "ToCounty",
label = "to",
choices=c(unique(emp_rate$countyname))
))),
actionButton("zoomer","go"),
leafletOutput("map")
)
)
)
)
)
server <- function(input, output, session) {
# map
output$map <- renderLeaflet({
mypal <- colorNumeric(palette="viridis", domain=states_sf_coef$rand_pred, na.color="transparent")
# mypalette(c(45,43))
leaflet() %>%
addProviderTiles("OpenStreetMap.Mapnik") %>%
setView(lat = 38.2393,
lng = -96.3795,
zoom = 4) %>%
addPolygons(
data = states_sf_coef,
fillColor = ~mypal(rand_pred),
# fillColor = ~ mypal(data$value),
stroke = FALSE,
smoothFactor = 0.2,
fillOpacity = 0.3,
popup = paste(
"Region: ",
states_sf_coef$countyname,
"<br>",
"Social Index: ",
states_sf_coef$rand_pred,
"<br>"
)
)
# %>%
# addLayersControl(
# baseGroups = c("Employment Prediction Data (default)", "To-From"),
# options = layersControlOptions(collapsed = FALSE)
# )
})
map_proxy <- leafletProxy("map")
observeEvent(input$zoomer, { # add Smith, county, kansas and default to zoom = 1?
# fromCounty
fromCountyInput <- reactive({
states_sf_coef %>% dplyr::filter(countyname == input$FromCounty)
})
fromData <- fromCountyInput()
fromCoords <- st_coordinates(st_centroid(fromData$geometry))
# toCounty
toCountyInput <- reactive({
states_sf_coef %>% dplyr::filter(countyname == input$ToCounty)
})
toData <- toCountyInput()
toCoords <- st_coordinates(st_centroid(toData$geometry))
map_proxy %>%
flyTo(lng = fromCoords[1], lat = fromCoords[2], zoom = 10)
flyTo(lng = toCoords[1], lat = toCoords[2], zoom = 10)
})
}
# Run the application
shinyApp(ui = ui, server = server)
Right now I'm getting the following error:
Warning: Error in dispatch: argument "map" is missing, with no default. Any guidance would be much appreciated!

Answer 1

I can't access your data to check that this works but I found a solution my (similar) problem by using shinyjs::delay(). This requires that you include the useShinyjs() in the ui as I have done below.
library(sf)
library(tigris)
library(shiny)
library(shinydashboard)
library(tidyverse)
library(leaflet)
library(shinyjs)
# data loading and processing
USA <- st_read(dsn = 'data/cb_2018_us_county_5m.shp')
counties_sf <- st_as_sf(USA)
counties_reproject_sf <- st_transform(counties_sf, 4326) %>% filter(COUNTYFP < 60010)
emp_rate <- read_csv('data/synthetic_emp_rate_pred.csv')
emp_rate$countyfips <- sprintf("%05d", emp_rate$countyfips)
states_sf_coef <- geo_join(counties_reproject_sf, emp_rate, "GEOID", "countyfips", how='inner')
ui <- fluidPage(
dashboardPage(
useShinyjs(),
dashboardHeader(title="Employee Rate Data"),
dashboardSidebar(
sidebarMenu(
menuItem(
"Maps",
tabName = "maps",
icon=icon("globe")
)
)
),
dashboardBody(
tabItems(
tabItem(
tabName = "maps",
tags$style(type="text/css","#all_airports {height:calc(100vh - 80px) !important;}"),
fluidRow(column(4),
column(8,
selectInput(inputId = "FromCounty",
label="from",
choices=c(unique(emp_rate$countyname)),
selected = 'Travis County, Texas'
),
selectInput(inputId = "ToCounty",
label = "to",
choices=c(unique(emp_rate$countyname))
))),
actionButton("zoomer","go"),
leafletOutput("map")
)
)
)
)
)
server <- function(input, output, session) {
# map
output$map <- renderLeaflet({
mypal <- colorNumeric(palette="viridis", domain=states_sf_coef$rand_pred, na.color="transparent")
# mypalette(c(45,43))
leaflet() %>%
addProviderTiles("OpenStreetMap.Mapnik") %>%
setView(lat = 38.2393,
lng = -96.3795,
zoom = 4) %>%
addPolygons(
data = states_sf_coef,
fillColor = ~mypal(rand_pred),
# fillColor = ~ mypal(data$value),
stroke = FALSE,
smoothFactor = 0.2,
fillOpacity = 0.3,
popup = paste(
"Region: ",
states_sf_coef$countyname,
"<br>",
"Social Index: ",
states_sf_coef$rand_pred,
"<br>"
)
)
# %>%
# addLayersControl(
# baseGroups = c("Employment Prediction Data (default)", "To-From"),
# options = layersControlOptions(collapsed = FALSE)
# )
})
map_proxy <- leafletProxy("map")
observeEvent(input$zoomer, { # add Smith, county, kansas and default to zoom = 1?
# fromCounty
fromCountyInput <- reactive({
states_sf_coef %>% dplyr::filter(countyname == input$FromCounty)
})
fromData <- fromCountyInput()
fromCoords <- st_coordinates(st_centroid(fromData$geometry))
# toCounty
toCountyInput <- reactive({
states_sf_coef %>% dplyr::filter(countyname == input$ToCounty)
})
toData <- toCountyInput()
toCoords <- st_coordinates(st_centroid(toData$geometry))
map_proxy %>%
flyTo(lng = fromCoords[1], lat = fromCoords[2], zoom = 10)
delay(5000, {map_proxy %>% flyTo(lng = toCoords[1], lat = toCoords[2], zoom = 10)})
})
}
# Run the application
shinyApp(ui = ui, server = server)