pyspark.sql.functions.first(col: ColumnOrName, ignorenulls: bool = False) → pyspark.sql.column.Column[source]

Aggregate function: returns the first value in a group.

The function by default returns the first values it sees. It will return the first non-null value it sees when ignoreNulls is set to true. If all values are null, then null is returned.

New in version 1.3.0.

Changed in version 3.4.0: Supports Spark Connect.

colColumn or str

column to fetch first value for.

ignorenullsColumn or str

if first value is null then look for first non-null value.


first value of the group.


The function is non-deterministic because its results depends on the order of the rows which may be non-deterministic after a shuffle.


>>> df = spark.createDataFrame([("Alice", 2), ("Bob", 5), ("Alice", None)], ("name", "age"))
>>> df = df.orderBy(df.age)
>>> df.groupby("name").agg(first("age")).orderBy("name").show()
| name|first(age)|
|Alice|      NULL|
|  Bob|         5|

Now, to ignore any nulls we needs to set ignorenulls to True

>>> df.groupby("name").agg(first("age", ignorenulls=True)).orderBy("name").show()
| name|first(age)|
|Alice|         2|
|  Bob|         5|