add_regular_polygon_grid
                        Add the rows needed to complete a regular
                        QuadKey polygon grid derived from the bounding
                        box of the 'quadkey' column of a data.frame.
apply_weekly_lag        Apply a 7 day lag to the variable 'n_crisis'
create_qk_grid          Create grid of QuadKeys for a particular zoom
                        or level of detail.
create_stars_raster     Create a 'stars' raster
format_fb_data          Format the Facebook mobility data
get_qk_coord            Get lat/long coordinates from the QuadKey
get_regular_polygon_grid
                        Get regular QuadKey polygon grid derived from
                        the bounding box of the 'quadkey' column of a
                        data.frame.
grid_to_polygon         Convert a grid of QuadKeys to square polygons
ground_res              Ground resolution at a specified latitude and
                        zoom level
latlong_to_pixelXY      Convert lat/long coordinates to pixel XY
                        coordinates
latlong_to_quadkey      Convert latitude/longitude coordinates into
                        QuadKeys
mapscale                Map scale (1 : N)
mapsize                 Map size in pixels
missing_combinations    Detect dates and hours missing in filenames
pixelXY_to_latlong      Convert pixel XY coordinatess into lat/long
                        coordinates.
pixelXY_to_tileXY       Convert pixel XY coordinates into tile XY
                        coordinates
polygon_to_raster       Create and save raster images for different
                        dates and times
qkmap_app               Launch the Shiny App
quadkey_df_to_polygon   Convert data.frame with 'quadkey' column to a
                        'sf' POLYGON data.frame
quadkey_to_latlong      Convert a string of Quadkey numbers to lat/long
                        coordinates
quadkey_to_polygon      Convert a QuadKey into a square polygon
quadkey_to_tileXY       Convert a QuadKey into tile XY coordinates.
read_fb_mobility_files
                        Read all the .csv files in a folder and format
                        the data.
regular_qk_grid         Convert a incomplete QuadKey 'sf' POINT
                        data.frame into a regular grid.
tileXY_to_pixelXY       Convert tile XY coordinates into pixel XY
                        coordinates
tileXY_to_quadkey       Convert tile XY coordinates into a QuadKey.
