Combine several points' criteria into one exact selection.
A point cloud's selection is a set of points rather than a cell, so a
highlight may cover many marks at once. Tableau combines criteria as a cross
product: [{A: [a1, a2]}, {B: [b1, b2]}] selects four marks, not two. So a
multi-point selection is expressible exactly only when the points differ in
exactly one field — then that field's values become the array and every other
field is a shared constant, which is precise because a detail dimension
identifies a row.
Anything else returns null and the caller clears instead. Over-selecting
would tell the reader that marks are highlighted which their cursor is not
on, which is worse than highlighting nothing.
Combine several points' criteria into one exact selection.
A point cloud's selection is a set of points rather than a cell, so a highlight may cover many marks at once. Tableau combines criteria as a cross product:
[{A: [a1, a2]}, {B: [b1, b2]}]selects four marks, not two. So a multi-point selection is expressible exactly only when the points differ in exactly one field — then that field's values become the array and every other field is a shared constant, which is precise because a detail dimension identifies a row.Anything else returns
nulland the caller clears instead. Over-selecting would tell the reader that marks are highlighted which their cursor is not on, which is worse than highlighting nothing.