h3_boundaryaswkt function

Returns the polygonal boundary of the input H3 cell in WKT format.

Since: Databricks Runtime 11.2

Syntax

h3_boundaryaswkt ( h3CellIdExpr )

Arguments

  • h3CellIdExpr: A BIGINT expression, or a hexadecimal STRING expression representing an H3 cell ID.

Returns

A value of the type STRING representing the polygonal boundary of the input H3 cell in WKT format.

The function returns NULL if the input expression is NULL. The function does partial validation regarding whether the input argument is a valid H3 cell ID. A necessary, but not sufficient condition for a valid H3 ID is that its value is between 0x08001fffffffffff and 0x08ff3b6db6db6db6. The behavior of the function is undefined if the input cell ID is not a valid cell ID.

Error conditions

  • If h3CellIdExpr is a STRING that cannot be converted to a BIGINT or corresponds to a BIGINT value that is either smaller than 0x08001fffffffffff or larger than 0x08ff3b6db6db6db6, the function returns H3_INVALID_CELL_ID.

Examples

-- Input a BIGINT representing a hexagonal cell.
> SELECT h3_boundaryaswkt(599686042433355775)
  POLYGON((-121.91508032706 37.271355866732,-121.86222328902 37.353926450852,-121.9235499963 37.428341186094,-122.03773496427 37.420128677678,-122.09042892904 37.337556084353,-122.02910130919 37.263197974618,-121.91508032706 37.271355866732))

-- Input a STRING representing a pentagonal cell.
> SELECT h3_boundaryaswkt('8009fffffffffff')
  POLYGON((-10.444977544778 63.095054077525,5.5236465492903 55.706768465152,25.082722326708 58.401544870353,31.831280499087 68.92995788194,0.32561035194326 73.310223685444,-10.444977544778 63.095054077525))

-- Input is an invalid H3 cell ID.
> SELECT h3_boundaryaswkt(0)
  [H3_INVALID_CELL_ID] 0 is not a valid H3 cell ID