How to get from dimensionality to a quantity?

[gsakkis]

Given a pint quantity, I can get its dimensionality:

In [1]: from pint import UnitRegistry

In [2]: U = UnitRegistry()

In [3]: q = U.Quantity("1m")

In [4]: dim = q.dimensionality

In [5]: dim
Out[5]: <UnitsContainer({'[length]': 1})>

How can I create a quantity given the dimensionality (assuming the base unit)? The following either fail or return bogus quantities:

In [6]: U(dim)
AttributeError: 'UnitsContainer' object has no attribute 'replace'

In [7]: U.Quantity(dim)
Out[7]: <UnitsContainer({'[length]': 1})> <Unit('dimensionless')>

In [8]: U.Quantity(1, dim)
Out[8]: 1 <Unit('[length]')>

[hgrecco]

There is no simple way now, but it would be good to add it.