keys() function

keys() returns the columns that are in the group key of each input table.

Each output table contains a row for each group key column label. A single group key column label is stored in the specified column for each row. All columns not in the group key are dropped.

Function type signature

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

Parameters

column

Column to store group key labels in. Default is _value.

tables

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

Examples

• Return group key columns for each input table
• Return all distinct group key columns in a single table
• Return group key columns as an array

Return group key columns for each input table

data
    |> keys()

Return all distinct group key columns in a single table

data
    |> keys()
    |> keep(columns: ["_value"])
    |> distinct()

Return group key columns as an array

1. Use keys() to replace the _value column with the group key labels.
2. Use findColumn() to return the _value column as an array.

import "sampledata"

sampledata.int()
    |> keys()
    |> findColumn(fn: (key) => true, column: "_value")// Returns [tag]