theta_union

Merges two binary representations of Datasketches ThetaSketch objects, using a Datasketches Union object.

Syntax

Python

from pyspark.sql import functions as sf

sf.theta_union(col1, col2, lgNomEntries=None)

Parameters

Parameter	Type	Description
col1	pyspark.sql.Column or str	The first Theta sketch.
col2	pyspark.sql.Column or str	The second Theta sketch.
lgNomEntries	pyspark.sql.Column or int, optional	The log-base-2 of nominal entries for the union operation (must be between 4 and 26, defaults to 12).

Returns

pyspark.sql.Column: The binary representation of the merged ThetaSketch.

Examples

Example 1: Union two Theta sketches

Python

from pyspark.sql import functions as sf
df = spark.createDataFrame([(1,4),(2,5),(2,5),(3,6)], "struct<v1:int,v2:int>")
df = df.agg(
    sf.theta_sketch_agg("v1").alias("sketch1"),
    sf.theta_sketch_agg("v2").alias("sketch2")
)
df.select(sf.theta_sketch_estimate(sf.theta_union(df.sketch1, "sketch2"))).show()

Output

+--------------------------------------------------------+
|theta_sketch_estimate(theta_union(sketch1, sketch2, 12))|
+--------------------------------------------------------+
|                                                       6|
+--------------------------------------------------------+