regex to extract only yy or yyyy

[snippsat]

You should post what you tried(like in working code),and also test example with input and wanted output
I can me a mess of text that you work with,or it can be more structured.

For the second pattern, I need to make sure that the year stands alone and has no more digits before or after.

>>> import re
>>> 
>>> s = '1980 100 18000 2000 112 2018'
>>> re.findall(r'(?<!\d)\d{4}(?!\d)', s)
['1980', '2000', '2018']

# only 2
>>> s = '19 100 18000 20 1234 1 55'
>>> re.findall(r'(?<!\d)\d{2}(?!\d)', s)
['19', '20', '55']