addAreaPolygons         Add Area Polygons to a Map
addCityShape            Adds a choropleth map layer for citys with
                        additional customization options.
addProvinceShape        Adds a choropleth map layer for provinces with
                        additional customization options.
addTilesAmap            Adds a tile layer from Amap to a leaflet map.
areaCalculator          Calculate the area of a polygon defined by
                        latitude and longitude points
china_city              city data for China
china_province          province data for China
convertCoordinates      Convert Coordinates Between Different Systems
