union

Aggregate Function

  union — set union of input values

Synopsis

union(any) -> |[any]|

Description

The union aggregate function computes a set union of its input values. If the values are of uniform type, then the output is a set of that type. If the values are of mixed typs, the the output is a set of union of the types encountered.

Examples

Create a set of values from a simple sequence:

echo '1 2 3 3' | zq -z 'union(this)' -

=>

|[1,2,3]|

Create sets continuously from values in a simple sequence:

echo '1 2 3 3' | zq -z 'yield union(this)' -

=>

|[1]|
|[1,2]|
|[1,2,3]|
|[1,2,3]|

Mixed types create a union type for the set elements:

echo '1 2 3 "foo"' | zq -z 'set:=union(this) | yield this,typeof(set)' -

=>

{set:|[1,2,3,"foo"]|}
<|[(int64,string)]|>

Create sets of values bucketed by key:

echo '{a:1,k:1} {a:2,k:1} {a:3,k:2} {a:4,k:2}' |
  zq -z 'union(a) by k | sort' -

=>

{k:1,union:|[1,2]|}
{k:2,union:|[3,4]|}