Set in Python (2)

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*Memo:

• My post explains a set and the set with copy.
• My post explains set functions (2).

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

*Memo:

• The 1st argument is elem(Required-Type:Any):
  • Don't use elem=.

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}

update() can add zero or more iterables to the set as shown below:

*Memo:

• The 1st arguments are *others(Optional-Default:()-Type:Iterable):
  • Don't use any keywords like *others=, others=, etc.
• |= with or without | also does update() but |= and | don't support the combination of the set and list or tuple.

A = {10, 30, 50}

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

A.update({20, 30, 40})
A.update([20, 30, 40])
A.update((20, 30, 40))
A.update({20, 30, 40}, [20, 30, 40], (20, 30, 40))

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

A.update()

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

A = {10, 30, 50}

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

A |= {20, 30, 40}
A |= {20, 30, 40} | {20, 30, 40} | {20, 30, 40}

print(A)
# {50, 20, 40, 10, 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=.

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=.

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.

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:

A = {10, 30, 50}

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

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

union() can return all the elements of the set and *others as shown below:

*Memo:

• The 1st arguments are *others(Optional-Default:()-Type:Iterable):
  • Don't use any keywords like *others=, others=, etc.
• | also does union() but | doesn't support the combination of a set and list or tuple.

A = {10, 50}
B = {10, 30, 50}
C = {20, 40}

print(A.union(B))    # {50, 10, 30}
print(A.union(C))    # {40, 10, 50, 20}
print(A.union(B, C)) # {50, 20, 40, 10, 30}
print(A.union())     # {10, 50}

print(A | B)     # {50, 10, 30}
print(A | C)     # {40, 10, 50, 20
print(A | B | C) # {50, 20, 40, 10, 30}
print(A)         # {10, 50}

A = {10, 50}     # set
B = [10, 30, 50] # list
C = (20, 40)     # tuple

print(A.union(B))    # {50, 10, 30}
print(A.union(C))    # {40, 10, 50, 20}
print(A.union(B, C)) # {50, 20, 40, 10, 30}
print(A.union())     # {10, 50}

intersection() can return the zero or more common elements of the set and *others as shown below:

*Memo:

• The 1st arguments are *others(Optional-Default:()-Type:Iterable):
  • Don't use any keywords like *others=, others=, etc.
• & also does intersection() but & doesn't support the combination of a set and list or tuple.
• intersection() creates a copy while intersection_update() doesn't.

A = {10, 20, 30, 40}
B = {10, 30, 50}
C = {30, 40}

print(A.intersection(B))    # {10, 30}
print(A.intersection(C))    # {40, 30}
print(A.intersection(B, C)) # {30}
print(A.intersection())     # {40, 10, 20, 30}

print(A & B)     # {10, 30}
print(A & C)     # {40, 30}
print(A & B & C) # {30}
print(A)         # {40, 10, 20, 30}

A = {10, 20, 30, 40} # set
B = [10, 30, 50]     # list
C = (30, 40)         # tuple

print(A.intersection(B))    # {10, 30}
print(A.intersection(C))    # {40, 30}
print(A.intersection(B, C)) # {30}
print(A.intersection())     # {40, 10, 20, 30}

intersection_update() can return the zero or more common elements of the set and *others as shown below:

*Memo:

• The 1st arguments are *others(Optional-Default:()-Type:Iterable):
  • Don't use any keywords like *others=, others=, etc.
• &= with or without & does intersection_update() but &= and & doesn't support the combination of a set and list or tuple.
• intersection_update() doesn't create a copy while intersection() does.

A = {10, 20, 30, 40}
B = {10, 30, 50}
C = {30, 40}

A.intersection_update(B)
print(A)
# {10, 30}

A.intersection_update(C)
print(A)
# {30}

A.intersection_update(B, C)
print(A)
# {30}

A.intersection_update()
print(A)
# {30}

A = {10, 20, 30, 40} # set
B = [10, 30, 50]     # list
C = (30, 40)         # tuple

A.intersection_update(B)
print(A)
# {10, 30}

A.intersection_update(C)
print(A)
# {30}

A.intersection_update(B, C)
print(A)
# {30}

A.intersection_update()
print(A)
# {30}

A = {10, 20, 30, 40}
B = {10, 30, 50}
C = {30, 40}

A &= B
print(A)
# {10, 30}

A &= C
print(A)
# {30}

A &= B & C
print(A)
# {30}