# create a new set

set1 = {1,2,3}

print(type(set1))  # result => <class 'set>

set2 = set()

print(type(set2))  # create an empty set, result => <class 'set'>

# as the object is iterable, we can create a set with list, tuple, dictionary etc.

list1 = [1, 2, 3]

set2 = set(list1)

print(set2, type(set2))

# {1, 2, 3} <class 'set'>

tuple1 = (1, 2, 3)

set2 = set(tuple1)

print(set2, type(set2))

# {1, 2, 3} <class 'set'>

dict1 = {'k1':1, 'k2':2}

set2 = set(dict1)

print(set2, type(set2))

# {'k1', 'k2'} <class 'set'>

# check if below is workable to create an empty set

set3 = {}

print(type(set3))

# type result => <class 'dict'> Failed

# so the variable_name = {} only works for creating a new dictionary 

# to add a new element, we can use add()

# as set only contains different elements, if we add the same element multiple times, only one will remain

set1 = {1, 2, 3, }

set1.add(4)

set1.add(4)

set1.add(4)

print(set1)

# result => {1, 2, 3, 4}

# to clear a set

set1.clear()

print(set1)

# => set()

# a.difference(b), elements in a but not in b

set1 = {1, 2, 3, 5, 8, }

set2 = {0, 1, 2, 3, }

ret1 = set1.difference(set2)

print(ret1)

# => {8, 5}

ret2 = set2.difference(set1)

print(ret2)

# => {0}

# difference() function does not change the set, if we want to change it, we can use difference_update()

set0 = {-1, }

set0.difference_update(set2)

print(set0)

# discard() to remove an element, if not a member, do nothing

set0 = {1, 2, 3, }

set0.discard(1)

print(set0)

set0.discard(-1)

print(set0)

# both print out: {2, 3}, no error msg

# if we use remove(), when the target element is not a member, there'll be error

# set0.remove(-1)

# print(set0)

'''

 Traceback (most recent call last):

set()

  File "D:/NaomiPyer/1016/1017_set_functions.py", line 44, in <module>

{8, 5}

    set0.remove(-1)

{0}

KeyError: -1

'''

# intersection(), gets the shared info

set1 = {1, 2, 3, 5, 8, }

set2 = {0, 1, 2, 3, }

ret3 = set1.intersection(set2)

print(ret3)

# => {1, 2, 3}

# a.intersection_update(b) update a with the intersection of a and b

set1 = {1, 2, 3, 5, 8, }

set2 = {0, 1, 2, 3, }

set1.intersection_update(set2)

print(set1)

# => {1, 2, 3, }

# isdisjoint() returns True if two sets has no intersection

set1 = {1, 2, 3, }

set2 = {0, }

ret1 = set1.isdisjoint(set2)

print(ret1)

# => True

set1 = {1, 2, 3, }

set2 = {1, }

ret1 = set1.isdisjoint(set2)

print(ret1)

# => False

# issubset() report whether another set contains this set

set1 = {1, }

set2 = {0, 1, 2, 3, }

ret1 = set1.issubset(set2)

print(ret1)

# => True, set1 is the subset of set2

# issuperset() is the opposite

ret1 = set1.issuperset(set2)

ret2 = set2.issuperset(set1)

print(ret1)  # False

print(ret2)  # True

# pop() remove and return an arbitrary set element.

# raises keyError if the set is empty

set1 = {1, 2, 3, 4, 6, }

ret1 = set1.pop()

print(set1)  # => {2, 3, 4, 6}

print(ret1)  # => 1

set1 = set()

ret1 = set1.pop()

print(set1)

print(ret1)  # KeyError: 'pop from an empty set' - like remove(), raises KeyError

# symmetric_difference()

# returns the symmetric difference of two sets as a new one

set1 = {0, 1, 2, }

set2 = {-1, 0, 3}

ret1 = set1.symmetric_difference(set2)

print(ret1)

# => {1, 2, 3, -1}

# symmetric_difference_update()

# update set1 with the result

set1 = {0, 1, 2, }

set2 = {-1, 0, 3}

set1.symmetric_difference_update(set2)

print(set1)

# => {1, 2, 3, -1}

# union() returns the union of sets as a new set

set1 = {0, 1, 2, }

set2 = {-1, 0, 3}

ret1 = set1.union(set2)

print(ret1)

# => {0, 1, 2, 3, -1}

# update() updates the set with the union of itself and the other set

set1 = {0, 1, 2, }

set2 = {-1, 0, 3}

set1.update(set2)

print(set1)

# => {0, 1, 2, 3, -1}

 import copy

 n1 = n1 = {

     'language': 'python',

     'IDE': 'PyCharm',

     'operating system': ['Linux', 'Windows']

 }

 n2 = copy.copy(n1)

 n3 = copy.deepcopy(n1)

 print(id(n1))  #

 print(id(n2))  #

 print(id(n3))  #

 # all id()'s are different