Test a "floor number" feature based on unit numbers

[jeancochrane]

Roughly 50% of condo PINs have unit identifiers that start with a number:

select numeric_unitno, count(*) as count
from (
    select
        case
            when
                unitno is not null
                and regexp_like(unitno, '^[0-9].*')
            then 'yes'
            else 'no'
        end as numeric_unitno
    from iasworld.pardat
    where cur = 'Y'
        and deactivat is null
        and class = '299'
) as unit_counts
group by numeric_unitno
order by numeric_unitno desc

#	numeric_unitno	count
1	yes	        6937526
2	no	        3501778

It's likely that for many buildings, particularly high rises, these numeric unit identifiers may be structured and contain information about the floor that the unit is on. We should try making a "floor number" feature based on unit identifiers in cases where the identifier appears to be numeric and follows the common pattern of a floor prefix with a unit suffix.