Zoom into Leaflet Map Based on User Inputs - r

Question

I am trying to figure out how to zoom into a map based on user inputs. I have started with the map of the US and then trying zooming into a specific location based on zip code and number of miles:
shinyUI(fluidPage(
# Application title
titlePanel("Starbucks Locator"),
# Sidebar with a slider input for number of bins
sidebarLayout(
sidebarPanel(
textInput("zip","Zip Code:", value = "18101"),
sliderInput("radius",
"Radius",
min = 1,
max = 25,
value = 15),
actionButton("go", "Submit")
),
# Show a plot of the generated distribution
mainPanel(
leafletOutput("myMap")
)
)
))
This is the Server Code:
library(shiny)
library(ZipRadius)
library(leaflet)
shinyServer(function(input, output) {
data <- reactive({x <- readRDS("Starbucks.rds")})
output$myMap <- renderLeaflet({
df <- data()
m <- leaflet(data = df) %>%
addTiles() %>%
addMarkers(lng = ~Lon, lat = ~Lat)
})
eventReactive(input$go, {
zip_include <- zipRadius(input$zip, input$radius)
})
leafletProxy("myMap") %>% fitBounds(~min(zip_include$longitude), ~min(zip_include$latitude),
~max(zip_include$longitude), ~max(zip_include$latitude))
})
I am using the ZipRadius package to find the which zip codes are input$distance away from input$zip. Then I want to zoom into the input zip code as the center and the bounds defined by the radius (input$distance). The original leaflet map works, but the leafletProxy is where I am having my issue. Any thoughts on how to do this? I am trying to use fitbounds since it can take into account minimum and maximum latitudes and longitudes. I think the issue may be with the eventReactive, but not sure how to test it. The dataset is available here at github.

Answer 1

There are a few issues with your server code.
You don't need to create your data in a reactive expression. As you only upload it once (I guess you won't change the coords or add another row).
Your renderLeaflet function can be simplified
Instead of using eventReactive use observeEvent. This function is triggered when you press the go button. In the observer you have to add all the actions that should be triggered by the button click. So you also have to insert the leafletProxy function here.
Remove the ~ symbol in the fitBounds function. You are already pointing to the zip_include dataset in fitBounds.
Working server (with provided csv)
shinyServer(function(input, output) {
data <- read.csv("c:/starbucks_us_locations.csv")
names(data) <- c('Lon', 'Lat')
output$myMap <- renderLeaflet({leaflet(data) %>%
addTiles() %>%
addMarkers(lng = ~Lon, lat = ~Lat)
})
observeEvent(input$go, {
zip_include <- zipRadius(input$zip, input$radius)
print(zip_include)
leafletProxy("myMap") %>% fitBounds(min(zip_include$longitude), min(zip_include$latitude),
max(zip_include$longitude), max(zip_include$latitude))
})
})