A different dimension from scale_example(), for the examples that need
two axes. Two frames, four atoms, its own key column (period) and a
weight – deliberately well behaved, so the awkwardness in an example stays
on the other axis.
scale_example2()A NestedScale with 4 atoms and frames era/period.
scale_example2()
#> NestedScale: example2
#> Description: Synthetic second dimension, for product examples
#> Frames (2, coarsest first):
#> - era (2)
#> - period (4)
#> Atoms: 4
#> Weights: span (default: span)
scale_product(a = scale_example(), b = scale_example2())
#> ScaleProduct: <unnamed>
#> Axes (2):
#> a : NestedScale 'example' sector/class/group/unit atoms 7 key: unit
#> b : NestedScale 'example2' era/period atoms 4 key: period
#> Atoms: 7 x 4 = 28 (not materialised)