Spark SQL Row_number() PartitionBy Sort Desc

Question

I\'ve successfully create a row_number() partitionBy by in Spark using Window, but would like to sort this by descending, instead of the default ascend

Answer 1

Update Actually, I tried looking more into this, and it appears to not work. (in fact it throws an error). The reason why it didn't work is that I had this code under a call to display() in Databricks (code after the display() call is never run). It seems like the orderBy() on a dataframe and the orderBy() on a window are not actually the same. I will keep this answer up just for negative confirmation

As of PySpark 2.4,(and probably earlier), simply adding in the keyword ascending=False into the orderBy call works for me.

Ex.

personal_recos.withColumn("row_number", F.row_number().over(Window.partitionBy("COLLECTOR_NUMBER").orderBy("count", ascending=False)))

and

personal_recos.withColumn("row_number", F.row_number().over(Window.partitionBy("COLLECTOR_NUMBER").orderBy(F.col("count").desc())))

seem to give me the same behaviour.

Answer 2

desc should be applied on a column not a window definition. You can use either a method on a column:

from pyspark.sql.functions import col, row_number
from pyspark.sql.window import Window

F.row_number().over(
    Window.partitionBy("driver").orderBy(col("unit_count").desc())
)

or a standalone function:

from pyspark.sql.functions import desc
from pyspark.sql.window import Window

F.row_number().over(
    Window.partitionBy("driver").orderBy(desc("unit_count"))
)

Answer 3

Or you can use the SQL code in Spark-SQL:

from pyspark.sql import SparkSession

spark = SparkSession\
    .builder\
    .master('local[*]')\
    .appName('Test')\
    .getOrCreate()

spark.sql("""
    select driver
        ,also_item
        ,unit_count
        ,ROW_NUMBER() OVER (PARTITION BY driver ORDER BY unit_count DESC) AS rowNum
    from data_cooccur
""").show()