Refactor this matrix into one with the same data,
but putting the given dimension in front.
This will speed up access to values with the given dimension.
If the dimension does not yet occur in the set (or any subset),
it is instantiated with a single nullValue value.
The set must be non-empty.
Refactor this matrix into one with the same data, but putting the given dimension in front. This will speed up access to values with the given dimension. If the dimension does not yet occur in the set (or any subset), it is instantiated with a single nullValue value. The set must be non-empty.