Check if string only contains characters from list of characters/symbols?

Question

How can I check in Python 3 that a string contains only characters/symbols from a given list?

Given:

• a list allowedSymbols = [\'b\', \'c\', \'z\', \'

Answer 1

Use sets for membership testing: keep the symbols in a set then check if it is a superset of the string.

>>> allowed = {'b', 'c', 'z', ':'}
>>> pass1 = 'b:c::z:bc:'
>>> allowed.issuperset(pass1)
True
>>> pass2 = 'f:c::z:bc:'
>>> allowed.issuperset(pass2)
False
>>> allowed.issuperset('bcz:')
True