first
Returns the first value in this DataColumn. If the DataColumn is empty, throws an exception.
API reference: first
df
df.name.first() // returns "Alice"
If a predicate is specified, returns the first value in this DataColumn that matches the predicate. Throws an exception if the DataColumn contains no elements matching the predicate.
df.age.first { it > 17 } // returns 20
firstOrNull
Returns the first value in this DataColumn. If the DataColumn is empty, returns null.
df
.filter { age > 50 } // df is empty after filtering
.age
.firstOrNull() // returns null
df
.filter { "age"<Int>() > 50 } // df is empty after filtering
.age
.firstOrNull() // returns null
If a predicate is specified, returns the first value in this DataColumn that matches the predicate, or null if the DataColumn contains no elements matching the predicate.
df.age.firstOrNull { it > 50 } // returns null
02 November 2026