Introduction

The code is used to create a Shiny app that allows the user to search for a type of amenity (such as a pharmacy) in a particular city, state, and country, and then display the results on a map. Here is a step-by-step explanation of how the code works.

Libraries

The code starts by loading four libraries – shiny, osmdata, mapview, and leaflet. These libraries contain functions that will be used later in the code.

User Interface

The user interface (UI) is defined using the fluidPage function from the shiny library. The UI consists of four text input boxes, a submit button, and a map output. The four text input boxes allow the user to enter the name of a city, state, and country, as well as the type of amenity they are looking for (e.g., pharmacy).

Server Function

The server function is where the “backend” of the app is defined. It is responsible for taking the user inputs, performing calculations or processing on them, and returning the output to the UI.

The server function is defined using the server function from the shiny library. Within the server function, we have an observeEvent function that listens for a click on the submit button. When the submit button is clicked, the function inside the observeEvent is executed.

Conclusion

In summary, this R code creates a Shiny app that allows the user to search for a specific type of amenity in a particular city, state, and country,

Full Application

Here is the full script of the app. Please steal this code and modify for yourself, see what you can come up with (PS it needs work for sure).

library(shiny)
library(osmdata)
library(mapview)
library(leaflet)

ui <- fluidPage(
  textInput("city", "City", placeholder = "e.g. Queens"),
  textInput("state", "State", placeholder = "e.g. New York"),
  textInput("country", "Country", placeholder = "e.g. USA"),
  textInput("amenity", "Amenity Type", placeholder = "e.g. pharmacy"),
  actionButton("submit", "Submit"),
  leafletOutput("map")
)

server <- function(input, output, session) {
  
  observeEvent(input$submit, {
    # Concatenate city, state, and country inputs into a single string
    address <- paste(input$city, input$state, input$country, sep = ", ")
    bbox <- getbb(address)
    query <- opq(bbox = bbox) |>
      add_osm_feature(key = "amenity", value = input$amenity)
    
    assign("has_internet_via_proxy", TRUE, environment(curl::has_internet))
    sf_obj <- osmdata_sf(query)
    m <- mapview(sf_obj$osm_points)
    output$map <- renderLeaflet({
      m@map
    })
  })
  
}

shinyApp(ui, server)

Voila!