Set & Frozenset functions in Python (1)

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*Memo:

• My post explains set and frozenset functions (2).
• My post explains set and frozenset functions (3).
• My post explains set and frozenset functions (4).
• My post explains a set (1).
• My post explains a frozenset (1).

add() can add a value to the set as shown below:

*Memo:

• The 1st argument is elem(Required-Type:Any):
  • Don't use elem=.
• add() doesn't create a new set.
• add() doesn't exist for a frozenset.

<Set>:

A = {10, 30, 50}

print(A)
# {10, 50, 30}

A.add(20)
print(A)
# {10, 50, 20, 30}

A.add(30)
print(A)
# {10, 50, 20, 30}

A.add(40)
print(A)
# {40, 10, 50, 20, 30}

A.add(50)
print(A)
# {40, 10, 50, 20, 30}

remove() can remove the element matched to elem from the set, getting error if the element doesn't exist in the set as shown below:

*Memo:

• The 1st argument is elem(Required-Type:Any):
  • Don't use elem=.
• remove() doesn't create a new set.
• remove() doesn't exist for a frozenset.

<Set>:

A = {10, 30, 50, 70}

print(A)
# {10, 50, 70, 30}

A.remove(50)
print(A)
# {10, 70, 30}

A.remove(70)
print(A)
# {10, 30}

A.remove(20)
# KeyError: 20

discard() can remove the element matched to elem from the set, not getting error even if the element doesn't exist in the set as shown below:

*Memo:

• The 1st argument is elem(Required-Type:Any):
  • Don't use elem=.
• discard() doesn't create a new set.
• discard() doesn't exist for a frozenset.

<Set>:

A = {10, 30, 50, 70}

print(A)
# {10, 50, 70, 30}

A.discard(50)
print(A)
# {10, 70, 30}

A.discard(70)
print(A)
# {10, 30}

A.discard(20)
print(A)
# {10, 30}

pop() can remove and throw an arbitrary element from the set as shown below:

*Memo:

• It has no arguments.
• Error occurs if the set is empty.
• pop() doesn't create a new set.
• pop() doesn't exist for a frozenset.

<Set>:

A = {10, 30, 50}

print(A) # {10, 50, 30}

print(A.pop()) # 10
print(A)       # {50, 30}

print(A.pop()) # 50
print(A)       # {30}

print(A.pop()) # 30
print(A)       # set()

print(A.pop())
# KeyError: 'pop from an empty set'

clear() can remove all elements from the set as shown below:

*Memo:

• It has no arguments.
• clear() doesn't create a new set.
• clear() doesn't exist for a frozenset.

<Set>:

A = {10, 30, 50}

print(A)
# {10, 50, 30}

A.clear()
print(A)
# set()