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.

Function	Syntax
Python	`convex_hull(geometry)`
SQL	`ST_ConvexHull(geometry)`

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

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

Examples

Python

SQL

Use dark colors for code blocksCopy
from geoanalytics.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.

Version table

Release	Notes
1.0.0	Function introduced

ST_ConvexHull

Examples

Version table

Related topics