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.


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