Dataframe 0.14 Help

join

Joins two DataFrame object by join columns.

join(otherDf, type = JoinType.Inner) [ { joinColumns } ] joinColumns: JoinDsl.(LeftDataFrame) -> Columns interface JoinDsl: LeftDataFrame { val right: RightDataFrame fun DataColumn.match(rightColumn: DataColumn) }

joinColumns is a column selector that defines column mapping for join:

df.join(other) { name match right.fullName }
val name by columnGroup() val fullName by columnGroup() df.join(other) { name match fullName }
df.join(other) { "name" match "fullName" }

If mapped columns have the same name, just select join columns from the left DataFrame:

df.join(other) { name and city }
val name by columnGroup() val city by column<String>() df.join(other) { name and city }
df.join(other, "name", "city")

If joinColumns is not specified, columns with the same name from both DataFrame objects will be used as join columns:

df.join(other)

Join types

Supported join types:

  • Inner (default) — only matched rows from left and right DataFrame objects

  • Filter — only matched rows from left DataFrame

  • Left — all rows from left DataFrame, mismatches from right DataFrame filled with null

  • Right — all rows from right DataFrame, mismatches from left DataFrame filled with null

  • Full — all rows from left and right DataFrame objects, any mismatches filled with null

  • Exclude — only mismatched rows from left DataFrame

For every join type there is a shortcut operation:

df.innerJoin(other) { name and city } df.leftJoin(other) { name and city } df.rightJoin(other) { name and city } df.fullJoin(other) { name and city } df.excludeJoin(other) { name and city }
val name by columnGroup() val city by column<String>() df.innerJoin(other) { name and city } df.leftJoin(other) { name and city } df.rightJoin(other) { name and city } df.fullJoin(other) { name and city } df.excludeJoin(other) { name and city }
df.innerJoin(other, "name", "city") df.leftJoin(other, "name", "city") df.rightJoin(other, "name", "city") df.fullJoin(other, "name", "city") df.excludeJoin(other, "name", "city")
Last modified: 27 September 2024