group

Partitions data by a field and wraps each partition's mark in a frame. Useful when you want a per-group enclosure that you can then style or reference, without imposing any spread/stack layout.

Signature

group({ by });

Parameters

Option	Type	Description
by	string	Required. Field to group by

Example

// One frame per species, with the per-species mark inside.
.flow(group({ by: "species" }))
.mark(area({ opacity: 0.7 }))

For most cases you'll want spread or stack instead — they group and lay out. Reach for group when you need named per-partition frames (e.g. for select or constraints) but don't want the children placed.