ST_ConvexHull

ST_ConvexHull takes a geometry column and returns a geometry column. The result column represents the convex hull of the input geometries in each record. A convex hull is the smallest geometry having only interior angles measuring less than 180° that encloses each input geometry. For multipoint, linestring, and polygon geometries, the result will be a polygon. For point geometries, the result is a point. The result column will always have the generic geometry type.

FunctionSyntax
Pythonconvex_hull(geometry)
SQLST_ConvexHull(geometry)
ScalaconvexHull(geometry)

For more details, go to the GeoAnalytics for Microsoft Fabric API reference for convex_hull.

This function implements the OpenGIS Simple Features Implementation Specification for SQL 1.2.1.

Python and SQL Examples

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from geoanalytics_fabric.sql import functions as ST

data = [
    ("POINT (10 30)",),
    ("MULTIPOINT (0 0, 5 5, 0 5)", ),
    ("LINESTRING (15 15, 10 15, 12 2)", ),
    ("POLYGON ((20 30, 18 28, 22 35, 40 20))", )
]

df = spark.createDataFrame(data, ["wkt"])\
          .select(ST.geom_from_text("wkt").alias("geometry"))

df = df.withColumn("convex_hull",ST.convex_hull("geometry"))

ax = df.st.plot("geometry", facecolor="none", edgecolor="red")
df.st.plot("convex_hull", ax=ax, facecolor="none", edgecolor="blue")
Plotting example for ST_ConvexHull
Plotted result for ST_ConvexHull.

Scala Example

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import com.esri.geoanalytics.sql.{functions => ST}

case class GeometryRow(wkt: String)
val data = Seq(GeometryRow("POINT (10 30)"),
               GeometryRow("MULTIPOINT (0 0, 5 5, 0 5)"),
               GeometryRow("LINESTRING (15 15, 10 15, 12 2)"),
               GeometryRow("POLYGON ((20 30, 18 28, 22 35, 40 20))"))

val df = spark.createDataFrame(data)
              .select(ST.geomFromText($"wkt").alias("geometry"))
              .withColumn("convex_hull",ST.convexHull($"geometry"))

df.select("convex_hull").show(truncate = false)
Result
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+---------------------------------------------+
|convex_hull                                  |
+---------------------------------------------+
|{"x":10,"y":30}                              |
|{"rings":[[[0,0],[0,5],[5,5],[0,0]]]}        |
|{"rings":[[[15,15],[12,2],[10,15],[15,15]]]} |
|{"rings":[[[18,28],[22,35],[40,20],[18,28]]]}|
+---------------------------------------------+

Version table

ReleaseNotes

1.0.0-beta

Python, SQL, and Scala functions introduced

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