Admin 0 & 1 interior singleton points

[xangregg]

I went through all the ~70 admin_x files looking for singleton interior points, as a diagnostic for potentially misaligned polygons (overlapping or gapped). These are minor in general, but the issues can worsen after downstream processing, such as polygon simplification.

For admin 0 and 1, I saw only one real singleton, which occurred in multiple files. Here they are as csv

shape# (1-based), part# (1-based), lon, lat, filename
6, 1, -57.63397091, -30.18358286, 10m_cultural/ne_10m_admin_0_countries_iso.shp
6, 1, -57.63397091, -30.18358286, 10m_cultural/ne_10m_admin_0_countries_tlc.shp
750, 1, -57.63397091, -30.18358286, 10m_cultural/ne_10m_admin_1_states_provinces_lakes.shp
774, 1, -57.63397091, -30.18358286, 10m_cultural/ne_10m_admin_1_states_provinces_scale_rank_minor_islands.shp
774, 1, -57.63397091, -30.18358286, 10m_cultural/ne_10m_admin_1_states_provinces_scale_rank.shp
750, 1, -57.63397091, -30.18358286, 10m_cultural/ne_10m_admin_1_states_provinces.shp

I spot-checked one of the non-offending files and it had this point twice, once each in two polygons.

Probably a non-issue but for completeness, in these files almost all of the interior points are singletons. Being all collinear, they're unlikely to cause problems downstream.

10m_cultural/ne_10m_admin_0_antarctic_claims.shp
10m_cultural/ne_10m_admin_0_pacific_groupings.shp
50m_cultural/ne_50m_admin_0_pacific_groupings.shp
110m_cultural/ne_110m_admin_0_pacific_groupings.shp

I'll make a separate issue for admin 2 singletons.