argwhichever

argwhichever, aggregator

def nosort process argwhichever() : boolean
def process argwhichever(t: boolean) : boolean

This aggregator returns true for one selected row within each group. In its no-argument version, it arbitrarily selects one row; in the version with a boolean condition provided as t, it returns true for one row where t is true.

Examples

Example 1: No-argument version

table Products = with
  [| as Label, as UnitPrice |]
  [| "Hat",    15.00        |]
  [| "Shirt",  15.00        |]
  [| "Pants",  25.00        |]

Products.IsTrue = argwhichever() by Products.UnitPrice

show table "" a1c3 with
  Products.Label
  Products.UnitPrice
  Products.IsTrue

One possible outcome is:

Note: In groups with multiple rows, the row marked true is chosen arbitrarily.

Example 2: With boolean condition

table Products = with
  [| as Label, as UnitPrice, as Eligible |]
  [| "Hat",    15.00,        false       |]
  [| "Shirt",  15.00,        true        |]
  [| "Pants",  25.00,        true        |]

Products.IsTrue = argwhichever(Products.Eligible) by Products.UnitPrice

show table "" a1c3 with
  Products.Label
  Products.UnitPrice
  Products.IsTrue

Based on the eligibility condition, the expected outcome is:

Note: Only rows meeting the boolean condition are eligible for selection.