question: public static int mapToGridCell ( float lon , float lat ) { int xIndex = ( int ) Math . floor ( ( Math . abs ( LON_WEST ) - Math . abs ( lon ) ) / DELTA_LON ) ; int yIndex = ( int ) Math . floor ( ( LAT_NORTH - lat ) / DELTA_LAT ) ; return xIndex + ( yIndex * NUMBER_OF_GRID_X ) ; }
target:  Maps a location specified by latitude and longitude values to a cell of a grid covering the area of NYC. The grid cells are roughly 100 x 100 m and sequentially number from north-west to south-east starting by zero.