Input DataFrame: rowsCount = 7, columnsCount = 5
nameagecityweightisHappy
firstNamelastName
AliceCooper15London54true
BobDylan45Dubai87true
CharlieDaniels20Moscownullfalse
CharlieChaplin40Milannulltrue
BobMarley30Tokyo68true
AliceWolf20null55false
CharlieByrd30Moscow90true

Step 1: Convert

class org.jetbrains.kotlinx.dataframe.api.Convert

Output DataFrame: rowsCount = 7, columnsCount = 5
nameagecityweightisHappy
{ firstName:Alice, lastName:Cooper }15London54true
{ firstName:Bob, lastName:Dylan }45Dubai87true
{ firstName:Charlie, lastName:Daniels }20Moscownullfalse
{ firstName:Charlie, lastName:Chaplin }40Milannulltrue
{ firstName:Bob, lastName:Marley }30Tokyo68true
{ firstName:Alice, lastName:Wolf }20null55false
{ firstName:Charlie, lastName:Byrd }30Moscow90true