Creates an interactive map for a data.frame containing point coordinates, colored by a selected variable.
Arguments
- df
 A data.frame containing columns for longitude and latitude.
- value
 A string giving the name of the column in
dfto be visualized.- lon
 A string with the name of the column containing longitude values. Default is
"lon".- lat
 A string with the name of the column containing latitude values. Default is
"lat".- crs
 Integer; EPSG code for the coordinate reference system. Default is
4326.- at
 Optional numeric vector; breakpoints used for visualization.
