pyspark.sql.functions.kll_merge_agg_double#

pyspark.sql.functions.kll_merge_agg_double(col, k=None)[source]#

Aggregate function: merges binary KllDoublesSketch representations and returns the merged sketch. The optional k parameter controls the size and accuracy of the merged sketch (range 8-65535). If k is not specified, the merged sketch adopts the k value from the first input sketch.

New in version 4.1.0.

Parameters

colColumn or column name: The column containing binary KllDoublesSketch representations
kColumn or int, optional: The k parameter that controls size and accuracy (range 8-65535)

Returns

Column: The merged binary representation of the KllDoublesSketch.

Examples

>>> from pyspark.sql import functions as sf
>>> df1 = spark.createDataFrame([1.0,2.0,3.0], "DOUBLE")
>>> df2 = spark.createDataFrame([4.0,5.0,6.0], "DOUBLE")
>>> sketch1 = df1.agg(sf.kll_sketch_agg_double("value").alias("sketch"))
>>> sketch2 = df2.agg(sf.kll_sketch_agg_double("value").alias("sketch"))
>>> merged = sketch1.union(sketch2).agg(sf.kll_merge_agg_double("sketch").alias("merged"))
>>> n = merged.select(sf.kll_sketch_get_n_double("merged")).first()[0]
>>> n
6