columns() function

columns() returns the column labels in each input table.

For each input table, columns outputs a table with the same group key columns and a new column containing the column labels in the input table. Each row in an output table contains the group key value and the label of one column of the input table. Each output table has the same number of rows as the number of columns of the input table.

Function type signature

(<-tables: stream[A], ?column: string) => stream[B] where A: Record, B: Record

Parameters

column

Name of the output column to store column labels in. Default is “_value”.

tables

Input data. Default is piped-forward data (<-).

Examples

List all columns per input table

import "sampledata"

sampledata.string()
    |> columns(column: "labels")