2 min read


pyspark-bucketmap is a tiny module for pyspark which allows you to bucketize DataFrame rows and map their values easily.
Photo by v2osk / Unsplash

Have you ever heard of pyspark's Bucketizer? It can be really useful! Although you perhaps won't need it for some simple transformation, it can be really useful for certain usecases.

In this blogpost, we will:

  1. Explore the Bucketizer class
  2. Combine it with create_map
  3. Use a module so we don't have to write the logic ourselves 🗝🥳

Let's get started!

The problem

First, let's boot up a local spark session:

from pyspark.sql import SparkSession

spark = SparkSession.builder.getOrCreate()

Say we have this dataset containing some persons:

from pyspark.sql import Row

people = spark.createDataFrame(
        Row(age=12, name="Damian"),
        Row(age=15, name="Jake"),
        Row(age=18, name="Dominic"),
        Row(age=20, name="John"),
        Row(age=27, name="Jerry"),
        Row(age=101, name="Jerry's Grandpa"),

Okay, that's great. Now, what we would like to do, is map each person's age to an age category.

age range life phase
0 to 12 Child
12 to 18 Teenager
18 to 25 Young adulthood
25 to 70 Adult
70 and beyond Elderly

How best to go about this?

Using Bucketizer + create_map

We can use pyspark's Bucketizer for this. It works like so:

from pyspark.ml.feature import Bucketizer
from pyspark.sql import DataFrame

bucketizer = Bucketizer(
    outputCol="life phase",
        -float("inf"), 0, 12, 18, 25, 70, float("inf")
bucketed: DataFrame = bucketizer.transform(people)
age name life phase
12 Damian 2.0
15 Jake 2.0
18 Dominic 3.0
20 John 3.0
27 Jerry 4.0
101 Jerry's Grandpa 5.0

Cool! We just put our ages in buckets, represented by numbers. Let's now map each bucket to a life phase.

from pyspark.sql.functions import lit, create_map
from typing import Dict
from pyspark.sql.column import Column

range_mapper = create_map(
    [lit(0.0), lit("Not yet born")]
    + [lit(1.0), lit("Child")]
    + [lit(2.0), lit("Teenager")]
    + [lit(3.0), lit("Young adulthood")]
    + [lit(4.0), lit("Adult")]
    + [lit(5.0), lit("Elderly")]
people_phase_column: Column = bucketed["life phase"]
people_with_phase: DataFrame = bucketed.withColumn(
    "life phase", range_mapper[people_phase_column]

age name life phase
12 Damian Teenager
15 Jake Teenager
18 Dominic Young adulthood
20 John Young adulthood
27 Jerry Adult
101 Jerry's Grandpa Elderly

🎉 Success!

Using a combination of Bucketizer and create_map, we managed to map people's age to their life phases.


🎁 As a bonus, I put all of the above in a neat little module, which you can install simply using pip.

%pip install pyspark-bucketmap

Define the splits and mappings like before. Each dictionary key is a mapping to the n-th bucket (for example, bucket 1 refers to the range 0 to 12).

from typing import List

splits: List[float] = [-float("inf"), 0, 12, 18, 25, 70, float("inf")]
mapping: Dict[int, Column] = {
    0: lit("Not yet born"),
    1: lit("Child"),
    2: lit("Teenager"),
    3: lit("Young adulthood"),
    4: lit("Adult"),
    5: lit("Elderly"),

Then, simply import pyspark_bucketmap.BucketMap and call transform().

from pyspark_bucketmap import BucketMap
from typing import List, Dict

bucket_mapper = BucketMap(
    splits=splits, mapping=mapping, inputCol="age", outputCol="phase"
phases_actual: DataFrame = bucket_mapper.transform(people).select("name", "phase")
name phase
Damian Teenager
Jake Teenager
Dominic Young adulthood
John Young adulthood
Jerry Adult
Jerry's Grandpa Elderly

Cheers 🙏🏻

You can find the module here:

Written by Jeroen Overschie, working at GoDataDriven.