CODEWITHSUNDEEP
pythonsqlapache-sparkdataframepyspark
martina.physics
martina.physics

Reputation: 9804

Filtering a Pyspark DataFrame with SQL-like IN clause

I want to filter a Pyspark DataFrame with a SQL-like IN clause, as in

sc = SparkContext()
sqlc = SQLContext(sc)
df = sqlc.sql('SELECT * from my_df WHERE field1 IN a')

where a is the tuple (1, 2, 3). I am getting this error:

java.lang.RuntimeException: [1.67] failure: ``('' expected but identifier a found

which is basically saying it was expecting something like '(1, 2, 3)' instead of a. The problem is I can't manually write the values in a as it's extracted from another job.

How would I filter in this case?

Upvotes: 58

Views: 120572

Answers (6)

user2662006
user2662006

Reputation: 2294

from pyspark.sql import SparkSession
import pandas as pd
spark=SparkSession.builder.appName('Practise').getOrCreate()
df_pyspark=spark.read.csv('datasets/myData.csv',header=True,inferSchema=True)
df_spark.createOrReplaceTempView("df") # we need to create a Temp table first
spark.sql("SELECT * FROM df where Departments in ('IOT','Big Data') order by Departments").show()

Upvotes: 0

shwetabharti
shwetabharti

Reputation: 141

Just a little addition/update:

choice_list = ["foo", "bar", "jack", "joan"]

If you want to filter your dataframe "df", such that you want to keep rows based upon a column "v" taking only the values from choice_list, then

from pyspark.sql.functions import col

df_filtered = df.where( ( col("v").isin (choice_list) ) )

Upvotes: 11

zero323
zero323

Reputation: 330453

String you pass to SQLContext it evaluated in the scope of the SQL environment. It doesn't capture the closure. If you want to pass a variable you'll have to do it explicitly using string formatting:

df = sc.parallelize([(1, "foo"), (2, "x"), (3, "bar")]).toDF(("k", "v"))
df.registerTempTable("df")
sqlContext.sql("SELECT * FROM df WHERE v IN {0}".format(("foo", "bar"))).count()
##  2

Obviously this is not something you would use in a "real" SQL environment due to security considerations but it shouldn't matter here.

In practice DataFrame DSL is a much better choice when you want to create dynamic queries:

from pyspark.sql.functions import col

df.where(col("v").isin({"foo", "bar"})).count()
## 2

It is easy to build and compose and handles all details of HiveQL / Spark SQL for you.

Upvotes: 80

BICube
BICube

Reputation: 4681

You can also do this for integer columns:

df_filtered = df.filter("field1 in (1,2,3)")

or this for string columns:

df_filtered = df.filter("field1 in ('a','b','c')")

Upvotes: 6

Alex_Gidiotis
Alex_Gidiotis

Reputation: 73

A slightly different approach that worked for me is to filter with a custom filter function.

def filter_func(a):
"""wrapper function to pass a in udf"""
    def filter_func_(col):
    """filtering function"""
        if col in a.value:
            return True

    return False

return udf(filter_func_, BooleanType())

# Broadcasting allows to pass large variables efficiently
a = sc.broadcast((1, 2, 3))
df = my_df.filter(filter_func(a)(col('field1'))) \

Upvotes: 0

braj
braj

Reputation: 2693

reiterating what @zero323 has mentioned above : we can do the same thing using a list as well (not only set) like below

from pyspark.sql.functions import col

df.where(col("v").isin(["foo", "bar"])).count()

Upvotes: 36

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