Missing G-W <1900 extinct polities

[JoeNoonan]

There are several polities that exist in G-W before the 19th century, that are now extinct, that are missing from both countrycode::countrylist and countrycode::codelist_panel.

Here is a (possibly incomplete) list:

gwcode	country_name	start	end
89	United Provinces of Central America	1823-07-01	1839-12-31
563	Transvaal	1852-01-01	1910-05-30
564	Orange Free State	1854-03-28	1910-05-30
711	Tibet	1913-01-01	1950-10-01
815	Vietnam (Annam/Cochin China/Tonkin)	1816-01-01	1893-01-01

Some of these units appear in other datasets in the countrylist data frame (United Provinces of Central America is in Polity as is Orange Free State) while others are totally absent (Transvaal, Tibet).

Vietnam is a bit difficult, because G-W codes Vietnam three different times: Vietnam (Annam/Cochin China/Tonkin) 1816-01-01 to 1893-01-01, Vietnam, Democratic Republic of 1954-05-01 to now, and Vietnam, Republic of, 1954-05-01to 1975-04-30. In the countrylist dataset on V-Dem codes are available <1954.

[vincentarelbundock]

@JoeNoonan Thanks a lot for raising this issue, I really appreciate it. Unfortunately, I don't have any bandwidth to deal with this right now, but the issue is in the repo and will eventually get addressed. Sorry for the delay!