ST_Z

ST_Z can work as a getter or a setter, depending on the inputs.

Getter: ST_Z takes a point column and returns a double column containing the z-coordinates of the input points. If a point does not have a z-coordinate the function returns NaN.

Setter: ST_Z takes a point column and a numeric value or column and returns a point column containing the input points with the z-coordinates set to the numeric value.

Function	Syntax
Python	`z(point, new_value=None)`
SQL	`ST_Z(point, new_value)`

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

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

Examples

Getter

Python

SQL

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from geoanalytics.sql import functions as ST

data = [
    ('{"x": -0.126,"y": 51.504,"z": 11253}',),
    ('{"x": -0.126,"y": 51.504}',)
]

df = spark.createDataFrame(data, ["esri_json"]) \
    .withColumn("point", ST.point_from_esri_json("esri_json"))

df.select(ST.z("point").alias("get_z")).show()

Result-as-getter
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+-------+
|  get_z|
+-------+
|11253.0|
|    NaN|
+-------+

Setter