rename

df.rename { columns }.into(name)
df.rename { columns }.into { nameExpression }

nameExpression = (DataColumn) -> String

df.rename { name }.into("fullName")

val name by columnGroup()
df.rename(name).into("fullName")

df.rename("name").into("fullName")

df.rename { age }.into {
    val mean = it.data.mean()
    "age [mean = $mean]"
}

val age by column<Int>()
df.rename(age).into {
    val mean = it.data.mean()
    "age [mean = $mean]"
}

df.rename("age").into {
    val mean = it.data.cast<Int>().mean()
    "age [mean = $mean]"
}

rename﻿