expr
inline fun <T, reified R> ColumnsSelectionDsl<T>.expr(name: String = "", infer: Infer = Infer.Nulls, noinline expression: AddExpression<T, R>): DataColumn<R>
Creates a temporary new column by defining an expression to fill up each row.
See Column Expression for more information.
For more information: See expr on the documentation website.
Check out: Grammar
For example:
df.groupBy{ expr{ firstName.length+ lastName.length} named"nameLength" }
df.sortBy{ expr{ name.length}.desc() }
Parameters
name
The name of the temporary column. Is empty by default ("untitled" in the DataFrame).
infer
org.jetbrains.kotlinx.dataframe.api.Infer.Infer that indicates how DataColumn.type should be calculated. Either None, Nulls, or Type. By default: Nulls.
expression
An AddExpression to define what each new row of the temporary column should contain.