Dealing with Nulls while FilteringΒΆ
Let us understand how to deal with nulls while filtering the data using Spark.
Let us start spark context for this Notebook so that we can execute the code provided. You can sign up for our 10 node state of the art cluster/labs to learn Spark SQL using our unique integrated LMS.
from pyspark.sql import SparkSession
import getpass
username = getpass.getuser()
spark = SparkSession. \
builder. \
config('spark.ui.port', '0'). \
config("spark.sql.warehouse.dir", f"/user/{username}/warehouse"). \
enableHiveSupport(). \
appName(f'{username} | Python - Basic Transformations'). \
master('yarn'). \
getOrCreate()
If you are going to use CLIs, you can use Spark SQL using one of the 3 approaches.
Using Spark SQL
spark2-sql \
--master yarn \
--conf spark.ui.port=0 \
--conf spark.sql.warehouse.dir=/user/${USER}/warehouse
Using Scala
spark2-shell \
--master yarn \
--conf spark.ui.port=0 \
--conf spark.sql.warehouse.dir=/user/${USER}/warehouse
Using Pyspark
pyspark2 \
--master yarn \
--conf spark.ui.port=0 \
--conf spark.sql.warehouse.dir=/user/${USER}/warehouse
employees = [(1, "Scott", "Tiger", 1000.0, 10,
"united states", "+1 123 456 7890", "123 45 6789"
),
(2, "Henry", "Ford", 1250.0, None,
"India", "+91 234 567 8901", "456 78 9123"
),
(3, "Nick", "Junior", 750.0, '',
"united KINGDOM", "+44 111 111 1111", "222 33 4444"
),
(4, "Bill", "Gomes", 1500.0, 10,
"AUSTRALIA", "+61 987 654 3210", "789 12 6118"
)
]
employeesDF = spark. \
createDataFrame(employees,
schema="""employee_id INT, first_name STRING,
last_name STRING, salary FLOAT, bonus STRING, nationality STRING,
phone_number STRING, ssn STRING"""
)
employeesDF.show()
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
| 1| Scott| Tiger|1000.0| 10| united states| +1 123 456 7890|123 45 6789|
| 2| Henry| Ford|1250.0| null| India|+91 234 567 8901|456 78 9123|
| 3| Nick| Junior| 750.0| |united KINGDOM|+44 111 111 1111|222 33 4444|
| 4| Bill| Gomes|1500.0| 10| AUSTRALIA|+61 987 654 3210|789 12 6118|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
Get all the records where bonus is not null or not empty.
employeesDF. \
filter("bonus IS NOT NULL"). \
show()
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
| 1| Scott| Tiger|1000.0| 10| united states| +1 123 456 7890|123 45 6789|
| 3| Nick| Junior| 750.0| |united KINGDOM|+44 111 111 1111|222 33 4444|
| 4| Bill| Gomes|1500.0| 10| AUSTRALIA|+61 987 654 3210|789 12 6118|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
employeesDF. \
filter("bonus <> ''"). \
show()
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
| 1| Scott| Tiger|1000.0| 10|united states| +1 123 456 7890|123 45 6789|
| 4| Bill| Gomes|1500.0| 10| AUSTRALIA|+61 987 654 3210|789 12 6118|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
employeesDF. \
filter("bonus IS NOT NULL AND bonus <> ''"). \
show()
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
| 1| Scott| Tiger|1000.0| 10|united states| +1 123 456 7890|123 45 6789|
| 4| Bill| Gomes|1500.0| 10| AUSTRALIA|+61 987 654 3210|789 12 6118|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
employeesDF. \
filter("!(bonus IS NULL OR bonus = '')"). \
show()
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
| 1| Scott| Tiger|1000.0| 10|united states| +1 123 456 7890|123 45 6789|
| 4| Bill| Gomes|1500.0| 10| AUSTRALIA|+61 987 654 3210|789 12 6118|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
from pyspark.sql.functions import col
c = col('X')
c.isNotNull?
Signature: c.isNotNull()
Docstring:
True if the current expression is NOT null.
>>> from pyspark.sql import Row
>>> df = spark.createDataFrame([Row(name='Tom', height=80), Row(name='Alice', height=None)])
>>> df.filter(df.height.isNotNull()).collect()
[Row(height=80, name='Tom')]
File: /usr/hdp/current/spark2-client/python/pyspark/sql/column.py
Type: method
employeesDF. \
filter((col('bonus').isNotNull()) &
(col('bonus') != '')
). \
show()
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
| 1| Scott| Tiger|1000.0| 10|united states| +1 123 456 7890|123 45 6789|
| 4| Bill| Gomes|1500.0| 10| AUSTRALIA|+61 987 654 3210|789 12 6118|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
employeesDF. \
filter((~ col('bonus').isNull()) &
(col('bonus') != '')
). \
show()
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
| 1| Scott| Tiger|1000.0| 10|united states| +1 123 456 7890|123 45 6789|
| 4| Bill| Gomes|1500.0| 10| AUSTRALIA|+61 987 654 3210|789 12 6118|
+-----------+----------+---------+------+-----+-------------+----------------+-----------+
Get all the records where bonus is null or empty.
employeesDF. \
filter("bonus IS NULL"). \
show()
+-----------+----------+---------+------+-----+-----------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus|nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+-----------+----------------+-----------+
| 2| Henry| Ford|1250.0| null| India|+91 234 567 8901|456 78 9123|
+-----------+----------+---------+------+-----+-----------+----------------+-----------+
employeesDF. \
filter("bonus = ''"). \
show()
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
| 3| Nick| Junior| 750.0| |united KINGDOM|+44 111 111 1111|222 33 4444|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
employeesDF. \
filter("bonus IS NULL OR bonus = ''"). \
show()
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
| 2| Henry| Ford|1250.0| null| India|+91 234 567 8901|456 78 9123|
| 3| Nick| Junior| 750.0| |united KINGDOM|+44 111 111 1111|222 33 4444|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
employeesDF. \
filter("nullif(bonus, '') IS NULL"). \
show()
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
| 2| Henry| Ford|1250.0| null| India|+91 234 567 8901|456 78 9123|
| 3| Nick| Junior| 750.0| |united KINGDOM|+44 111 111 1111|222 33 4444|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
c.isNull?
Signature: c.isNull()
Docstring:
True if the current expression is null.
>>> from pyspark.sql import Row
>>> df = spark.createDataFrame([Row(name='Tom', height=80), Row(name='Alice', height=None)])
>>> df.filter(df.height.isNull()).collect()
[Row(height=None, name='Alice')]
File: /usr/hdp/current/spark2-client/python/pyspark/sql/column.py
Type: method
employeesDF. \
filter((col('bonus').isNull()) |
(col('bonus') == '')
). \
show()
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
| 2| Henry| Ford|1250.0| null| India|+91 234 567 8901|456 78 9123|
| 3| Nick| Junior| 750.0| |united KINGDOM|+44 111 111 1111|222 33 4444|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
employeesDF. \
filter((col('bonus').cast('int').isNull())
). \
show()
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
|employee_id|first_name|last_name|salary|bonus| nationality| phone_number| ssn|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+
| 2| Henry| Ford|1250.0| null| India|+91 234 567 8901|456 78 9123|
| 3| Nick| Junior| 750.0| |united KINGDOM|+44 111 111 1111|222 33 4444|
+-----------+----------+---------+------+-----+--------------+----------------+-----------+