findColumn() function

The findColumn() function returns an array of values in a specified column from the first table in a stream of tables where the group key values match the specified predicate. The function returns an empty array if no table is found or if the column label is not present in the set of columns.

findColumn(
    fn: (key) => key._field == "fieldName",
    column: "_value",
)

Parameters

fn

A predicate function for matching keys in a table’s group key. Expects a key argument that represents a group key in the input stream.

column

Name of the column to extract.

tables

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

Example

The following example uses data provided by the sampledata package to show how findColumn() transforms data.

import "sampledata"

sampledata.int()
    |> findColumn(fn: (key) => key.tag == "t1", column: "_value")
    
// Returns [-2, 10, 7, 17, 15, 4]