Consider -4 values in wof:parent_id property

[stepps00]

Similar to how we use the -3 value in the wof:parent_id property, we use a -4 property to represent multiple "legal" parents (see: New York City).

The hierarchy library has rules and references -3 values and should be updated to also handle -4 values in the wof:parent_id property.

Occurances:

• https://github.com/whosonfirst/py-mapzen-whosonfirst-hierarchy/blob/master/mapzen/whosonfirst/hierarchy/__init__.py#L50
• https://github.com/whosonfirst/py-mapzen-whosonfirst-hierarchy/blob/master/mapzen/whosonfirst/hierarchy/__init__.py#L297
• https://github.com/whosonfirst/py-mapzen-whosonfirst-hierarchy/blob/master/mapzen/whosonfirst/hierarchy/__init__.py#435

[thisisaaronland]

@stepps00 – The first two cases have been addressed. What is / are the conditions that would flag a parent as -4 ? For example, a parent ID of -3 is assigned when:

        ambiguous = [ 'neighbourhood', 'microhood', 'campus', 'address', 'building', 'venue' ]
        self.is_ambiguous = ambiguous

        if feature['properties']['wof:placetype'] in self.is_ambiguous:
             feature['properties']['wof:parent_id'] = -3

[stepps00]

@thisisaaronland - The only difference should be the record's placetype. We discussed a -4 being assigned whenever there is a legal argument around its parents, which would likely only happen to a placetype of locality or above..

I would expect the parent value to be assigned through something like:

        ambiguous_three = [ 'borough', 'macrohood', 'neighbourhood', 'microhood', 'campus', 'address', 'building', 'venue' ]
        self.is_ambiguous = ambiguous_three

        if feature['properties']['wof:placetype'] in self.is_ambiguous:
             feature['properties']['wof:parent_id'] = -3

and

        ambiguous_four = [ 'locality', 'macroregion', 'region', 'macrocounty', 'county']
        self.is_ambiguous = ambiguous_four

        if feature['properties']['wof:placetype'] in self.is_ambiguous:
             feature['properties']['wof:parent_id'] = -4