Have you seen web pages screeming "Put me on a map !" ?
One of them is French Tech Visa. There is company info and search by area, but no map.
Here is a live geocoded map for the same page which could be used for location search. (data as of Dec 2017)
Click on a map marker to see details here
Luckily, all the data was inside the page source in JSON format. To clean and use it in R, one could simply copy and assign it to a variable, then source it in RStudio to fix any errors. Then it can be converted to a data.frame.
Next step was to extract the addresses (companies[1:100,]$Adresse), clean them of special characters and try a batch geocode online. From the KML output file, one could extract the lon/lat coordinates and match them to the companies by address.
As a result, the companies data frame gets two more columns - latitude and longitude. We saved this geocoded data in a second JSON file.
xjson <- jsonlite::toJSON(companies, pretty=T)
out <- file('french.json', encoding="UTF-8")
Photos on a map
Below is a demo clip of another Leaflet map. Hover mouse on (green) markers will show related images. Images could be dragged over the map, zoomed along with the map, or closed by double-click.
GIS projects ofter require spatial measurements. In the sample below, given a set of points (Lat/Lon coordinates), the goal is to find which ones are within 5 km distance from two predefined locations. By drawing a circle (radius 5km) from each location, all points inside the intersection area meet the requirement.
Coded in R, the steps accomplished for this project were:
load US census boundary and attribute data
cleanup blocks outside city area
build interactive map with census blocks color-coded by population