df.add { "year" from { 0 } }

Input DataFrame: rowsCount = 7, columnsCount = 5

name		age	city	weight	isHappy
firstName	lastName
Alice	Cooper	15	London	54	true
Bob	Dylan	45	Dubai	87	true
Charlie	Daniels	20	Moscow	null	false
Charlie	Chaplin	40	Milan	null	true
Bob	Marley	30	Tokyo	68	true
Alice	Wolf	20	null	55	false
Charlie	Byrd	30	Moscow	90	true

Output DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

df.select { cols { it.name().startsWith("year") } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 1

year
0
0
0
0
0
0
0

df.select { nameStartsWith("year") }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 1

year
0
0
0
0
0
0
0

df.select { colsOf<String>() }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 0, columnsCount = 0

df.select { colsOf<String?> { it.countDistinct() > 5 } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 1

city
London
Dubai
Moscow
Milan
Tokyo
null
Moscow

df.select { all() }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

df.select { take(2) }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 2

name		age
firstName	lastName
Alice	Cooper	15
Bob	Dylan	45
Charlie	Daniels	20
Charlie	Chaplin	40
Bob	Marley	30
Alice	Wolf	20
Charlie	Byrd	30

df.select { takeLast(2) }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 2

isHappy	year
true	0
true	0
false	0
true	0
true	0
false	0
true	0

df.select { drop(2) }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 4

city	weight	isHappy	year
London	54	true	0
Dubai	87	true	0
Moscow	null	false	0
Milan	null	true	0
Tokyo	68	true	0
null	55	false	0
Moscow	90	true	0

df.select { dropLast(2) }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 4

name		age	city	weight
firstName	lastName
Alice	Cooper	15	London	54
Bob	Dylan	45	Dubai	87
Charlie	Daniels	20	Moscow	null
Charlie	Chaplin	40	Milan	null
Bob	Marley	30	Tokyo	68
Alice	Wolf	20	null	55
Charlie	Byrd	30	Moscow	90

df.select { first { it.name.startsWith("year") } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 1

year
0
0
0
0
0
0
0

df.select { colGroup("name").lastCol { it.name().endsWith("Name") } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 1

lastName
Cooper
Dylan
Daniels
Chaplin
Marley
Wolf
Byrd

df.select { Person::name.singleCol { it.name().startsWith("first") } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 1

firstName
Alice
Bob
Charlie
Charlie
Bob
Alice
Charlie

df.select { colsAtAnyDepth().filter { !it.isColumnGroup() } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 7

firstName	lastName	age	city	weight	isHappy	year
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

df.select { colsAtAnyDepth() }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 8

name		firstName	lastName	age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	Alice	Cooper	15	London	54	true	0
Bob	Dylan	Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	Alice	Wolf	20	null	55	false	0
Charlie	Byrd	Charlie	Byrd	30	Moscow	90	true	0

df.select { colsAtAnyDepth().filter() { it.name().contains(":") } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 0, columnsCount = 0

df.select { colsAtAnyDepth().colsOf<String>() }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 2

firstName	lastName
Alice	Cooper
Bob	Dylan
Charlie	Daniels
Charlie	Chaplin
Bob	Marley
Alice	Wolf
Charlie	Byrd

df.select { allExcept { colsOf<String>() } }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

df.select { take(2) and col(3) }

Input DataFrame: rowsCount = 7, columnsCount = 6

name		age	city	weight	isHappy	year
firstName	lastName
Alice	Cooper	15	London	54	true	0
Bob	Dylan	45	Dubai	87	true	0
Charlie	Daniels	20	Moscow	null	false	0
Charlie	Chaplin	40	Milan	null	true	0
Bob	Marley	30	Tokyo	68	true	0
Alice	Wolf	20	null	55	false	0
Charlie	Byrd	30	Moscow	90	true	0

Output DataFrame: rowsCount = 7, columnsCount = 3

name		age	weight
firstName	lastName
Alice	Cooper	15	54
Bob	Dylan	45	87
Charlie	Daniels	20	null
Charlie	Chaplin	40	null
Bob	Marley	30	68
Alice	Wolf	20	55
Charlie	Byrd	30	90