'''
20210928

Robin Dawes

Creating and using sets
'''
# Create a set and initialize it.
# Note that we use { } here, just as for dictionaries
cheerful = {'Kim', 'Pat', 'Ricky', 'Terry', 'Parker', 'Brady', 'Jay'}

# Create an empty set
artistic = set()

# Add some new elements one at a time using "add"
artistic.add('Gabriel')
artistic.add('Skyler')
# Add new elements in batches using "update"
# The argument to "update" can be any iterable object
artistic.update( {'Ricky', 'Shay'})
# Note that we are attempting to add an element that is already in the set ("Shay")
# This does not cause an error
# The element does not get duplicated - sets contain no duplicates
artistic.update( ['Shay', 'Pat'] )

# printing a set all at once
print(cheerful)
print(artistic)

# iterating through a set
for n in cheerful:
   print(n)

# removing an element
print("\nRemove Terry")   
# trying to remove an element that is not there will cause an error 
cheerful.remove('Terry')
print(cheerful)

# discarding an element
print("\nDiscard Parker and Keagan (who?)")
cheerful.discard('Parker')
# trying to discard an element that is not there will NOT cause an error
cheerful.discard('Keagan')
print(cheerful)

# create the union of two sets
print("\nUnion")
everyone = cheerful.union(artistic)
print(everyone)

# create the intersection of two sets
print("\nIntersection")
people_in_both = cheerful.intersection(artistic)
print(people_in_both)

# create the symmetric difference of two sets
print("\nSymmetric Difference")
one_but_not_both = cheerful.symmetric_difference(artistic)
print(one_but_not_both)

# test to see if one set is a subset of another set
print("\nSubset")
painters = {'Skyler', 'Ricky'}
print(painters)

if painters.issubset(artistic):
   print ("painters is a subset of artistic")
else:
   print  ("painters is not a subset of artistic")
   
# there are many more set operations!