Interactive R Map with Search Functionality

Question

Trying to build a very basic interactive map in R. In general I would like to do the following:

Export a shapefile from ArcGIS -> Plot as interactive map in R -> Search shapefile based on attributes (e.g. Name)

I have been using tmap:

shapefile = st_read("C:/Projects/_SANDBOX/R/Shapefiles/XXX.shp")
map = tm_shape(shapefile)+tm_fill(col="blue",alpha=0.3) +tm_borders(col="black")
tmap_mode("view")
map

But I am stuck at the point of trying to add the search function. Would it be better/easier to do this sort of thing using leaflet in R? If so how would that look?

Any help is greatly appreciated. Thanks!

I'm unaware of a built-in search box function in either `leaflet` or `tmap`. My initial thoughts would probably involve making a `shiny` app - and having a search box (text input) in the app where you can search for or select (drop down box) from a list of feature names in your data/map. Then, the map could re-centre on (the centroid of) this feature. The map will begin to stray away from "very basic interactive map" status, but is certainly achievable and should be relatively straightforward to build. It will still appear to the user as "very basic". — hugh-allan, Oct 21 '21 at 01:22

hugh-allan · Accepted Answer · 2021-10-21T07:03:51.430

Like I said in my comment, I'm unaware of a built-in search function in leaflet or tmap, so my first thoughts were to utilise shiny as the searching component and map display.

This is a pretty basic example, but allows you to select a country to zoom in on from a drop-down list. The selected country is coloured in red in the world map, and is shown in the initial frame/position of the map when opened, using the bbox argument of tm_shape(). The country is separated from the rest of the world using filter(), and saved as my_country; this is used to plot the selected country as the red layer, and also as the zoom position by retrieving it's coordinates using sf::st_bbox().

library(shiny)
library(tidyverse)
library(tmap)
library(spData)
library(sf)
tmap_mode('view')

# Define UI for application that draws a histogram
ui <- fluidPage(

    # Application title
    titlePanel('Search the world'),

    # Sidebar with a drop down boxz for country names
    sidebarLayout(
        sidebarPanel(
            selectInput(inputId = 'country',
                        label = 'Country to zoom in on:',
                        choices = world$name_long)
        ),

        # Show the map
        mainPanel(
           tmapOutput('map')
        )
    )
)

# Define server logic required to make the map
server <- function(input, output) {
    
    # build the map
    output$map <- renderTmap({

        my_country <- world %>% 
            filter(
                name_long == input$country
            )
        
        tm_shape(world, bbox = st_bbox(my_country))+
            tm_polygons()+
            tm_shape(my_country)+
            tm_polygons(col = 'red')

    })
    
}

# Run the application 
shinyApp(ui = ui, server = server)

Of course you could modify the inputs and outputs as you please. I chose a drop down box because it means you won't misspell a country name; unlike something like Google Maps which might be able to handle misspelt place names, filter() requires the names match exactly.

Although it's a drop down box, there seems to be some limited search functionality within it; if you delete the name in the box and start typing, matching country names will present themselves:

Interactive R Map with Search Functionality

1 Answers1