desc_nulls_first
Returns a sort expression based on the descending order of the given column name, and null values appear before non-null values. Supports Spark Connect.
Syntax
Python
from pyspark.sql import functions as dbf
dbf.desc_nulls_first(col=<col>)
Parameters
Parameter | Type | Description |
|---|---|---|
|
| Target column to sort by in the descending order. |
Returns
pyspark.sql.Column: the column specifying the order.
Examples
Example 1: Sorting a DataFrame with null values in descending order.
Python
from pyspark.sql import functions as dbf
df = spark.createDataFrame([(1, "Bob"), (0, None), (2, "Alice")], ["age", "name"])
df.sort(dbf.desc_nulls_first(df.name)).show()
Output
+---+-----+
|age| name|
+---+-----+
| 0| NULL|
| 1| Bob|
| 2|Alice|
+---+-----+
Example 2: Sorting a DataFrame with null values in descending order using column name string.
Python
from pyspark.sql import functions as dbf
df = spark.createDataFrame([(1, "Bob"), (0, None), (2, "Alice")], ["age", "name"])
df.sort(dbf.desc_nulls_first("name")).show()
Output
+---+-----+
|age| name|
+---+-----+
| 0| NULL|
| 1| Bob|
| 2|Alice|
+---+-----+