single
Returns the single value in this DataColumn. Throws NoSuchElementException if the DataColumn is empty, and IllegalArgumentException if it contains more than one value.
API reference: single
df
df
.filter { name == "Bob" } // one row is left after filtering
.age
.single() // returns 20
df
.filter { "name"<String>() == "Bob" } // one row is left after filtering
.age
.single() // returns 20
Use first or last when the DataColumn may contain more than one value, and firstOrNull when it may be empty — there is no singleOrNull for a DataColumn.
02 November 2026