Create simple geometries from ordered rows of GeoPoints

Supported in: Batch

Given a column of GeoPoints and an ordering, return either a polygon or a line string by connecting the GeoPoints in the specified order. This function assumes that the data is tabular, with a single row representing an individual GeoPoint in a line string or in the shell of a polygon, along with a column specifying the order of those points. For a polygon this ordering should identify the points as you move counter-clockwise around the shell. Given an ordering of these points and a partition (grouping), the function constructs the required geometry for that partition by joining the GeoPoints in ascending order of the order-by column.

Expression categories: Geospatial

Declared arguments

GeoPoint - A column of GeoPoints from which the geometry is constructed. Each row in the dataset should represent an individual GeoPoint. If there are null values, these rows are ignored.
Expression<GeoPoint>
Order by (ascending) - A column of values by which the GeoPoints will be ordered to construct the line string or the shell of the desired polygon. The ordering is random if values are identical within a group. If there are null values, those rows are ignored.
Expression<Byte | Date | Decimal | Double | Float | Integer | Long | Short | Timestamp>
Output geometry type - Whether the output should be a polygon or a line-string.
Enum<LineString, Polygon>

Output type: Geometry

Examples

Example 1: Base case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: LINE_STRING

Given input table:

geo_point	order
{ latitude -> 0.0, longitude -> 0.0, }	0
{ latitude -> 1.0, longitude -> 0.0, }	1
{ latitude -> 1.0, longitude -> 1.0, }	2

Outputs: {"type":"LineString","coordinates": [[0.0,0.0],[0.0, 1.0],[1.0,1.0]]}

Example 2: Base case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: POLYGON

Given input table:

geo_point	order
{ latitude -> 0.0, longitude -> 0.0, }	0
{ latitude -> 1.0, longitude -> 0.0, }	3
{ latitude -> 1.0, longitude -> 1.0, }	2
{ latitude -> 0.0, longitude -> 0.0, }	4
{ latitude -> 0.0, longitude -> 1.0, }	1

Outputs: {"type":"Polygon","coordinates": [[[0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], [0.0, 0.0]]]}

Example 3: Base case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: LINE_STRING

Given input table:

geo_point	order
{ latitude -> 0.0, longitude -> 0.0, }	0.0
null	1.0
null	2.0
{ latitude -> 0.0, longitude -> 1.0, }	2.0

Outputs: {"type":"LineString","coordinates": [[0.0,0.0],[1.0, 0.0]]}

Example 4: Base case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: LINE_STRING

Given input table:

geo_point	order
{ latitude -> 0.0, longitude -> 0.0, }	0.0

Outputs: null

Example 5: Base case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: POLYGON

Given input table:

geo_point	order
{ latitude -> 0.0, longitude -> 0.0, }	0
{ latitude -> 1.0, longitude -> 1.0, }	2
{ latitude -> 1.0, longitude -> 0.0, }	3
{ latitude -> 0.0, longitude -> 1.0, }	1

Outputs: {"type":"Polygon","coordinates": [[[0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], [0.0, 0.0]]]}

Example 6: Base case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: POLYGON

Given input table:

geo_point	order
{ latitude -> 0.0, longitude -> 0.0, }	0
{ latitude -> 1.0, longitude -> 0.0, }	1

Outputs: null

Example 7: Null case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: POLYGON

Given input table:

geo_point	order
null	0

Outputs: null

Example 8: Null case

Argument values:

GeoPoint: geo_point
Order by (ascending): order
Output geometry type: LINE_STRING

Given input table:

geo_point	order
{ latitude -> 0.0, longitude -> 0.0, }	0
{ latitude -> 1.0, longitude -> 1.0, }	null
{ latitude -> 1.0, longitude -> 0.0, }	1

Outputs: {"type":"LineString","coordinates": [[0.0,0.0],[0.0, 1.0]]}