set:
- Set object can be created by using curly brackets { },or by calling set function.
- Insertion order is not preserved.
- Duplicate elements are not allowed.
- Heterogeneous elements are allowed.
- Set is a mutable object but the elements must be immutable.
- Set object doesn't support indexing.
- We can perform the mathematical set operations like union, intersection, difference, symmetric difference on set objects.
a={10,20,30}
print(a)
print(type(a))
{10, 20, 30}
<class 'set'>
b=set()
print(b)
print(type(b))
set()
<class 'set'>
c={1,2.3,4+3j,True,"sivakrishna"}
print(c)
{1, 2.3, 'sivakrishna', (4+3j)}
d={10,20,10,30,20}
print(d)
{10, 20, 30}
- list inside list is allowed
- tuple inside tuple is allowed
- But set inside set is not allowed
- set inside list not support
- set inside tuple support
e={{1,2,3},{'siva','krishna'}}
print(e)
Traceback (most recent call last):
File "E:/python_practice/examples/set.py", line 1, in <module>
e={{1,2,3},{'siva','krishna'}}
TypeError: unhashable type: 'set'
f={[10,20,30],['siva','krishna']}
print(f)
Traceback (most recent call last):
File "E:/python_practice/examples/set.py", line 1, in <module>
f={[10,20,30],['siva','krishna']}
TypeError: unhashable type: 'list'
g={(10,20,30),('siva','krishna')}
print(g)
{(10, 20, 30), ('siva', 'krishna')}
- In set object not perform while loop, here perform for loop. because set object not support indexing.
- for loop working not based on indexes
- while loop working based on indexes
a={10,20,30}
print(a)
print(type(a))
print(a[2])
Traceback (most recent call last):
File "E:/python_practice/examples/set.py", line 4, in <module>
print(a[2])
TypeError: 'set' object does not support indexing
x={(1,2,3),('siva','krishna'),(3+4j,True)}
print(x)
for p in x:
print(p,type(p))
{((3+4j), True), ('siva', 'krishna'), (1, 2, 3)}
((3+4j), True) <class 'tuple'>
('siva', 'krishna') <class 'tuple'>
(1, 2, 3) <class 'tuple'>
y={10,20,30,40,50}
print(y)
print(len(y))
i=0
while i<len(y):
print(y[i])
i=i+1
{40, 10, 20, 50, 30}
5
Traceback (most recent call last):
File "E:/python_practice/examples/set.py", line 4, in <module>
print(y[i])
TypeError: 'set' object does not support indexing
Python Set Methods
There are many set methods,
some of which we have already used above. Here is a list of all the methods
that are available with set objects.
|
Python
Set Methods
|
|
|
Method
|
Description
|
|
add()
|
Add an element to a set
|
|
clear()
|
Remove all elemets form a set
|
|
copy()
|
Return a shallow copy of a set
|
|
difference()
|
Return the difference of two or more sets as
a new set
|
|
difference_update()
|
Remove all elements of another set from this
set
|
|
discard()
|
Remove an element from set if it is a
member. (Do nothing if the element is not in set)
|
|
intersection()
|
Return the intersection of two sets as a new
set
|
|
intersection_update()
|
Update the set with the intersection of
itself and another
|
|
isdisjoint()
|
Return True if two sets have a null intersection
|
|
issubset()
|
Return True if another set contains this set
|
|
issuperset()
|
Return True if this set contains another set
|
|
pop()
|
Remove and return an arbitrary set element.
Raise KeyError if
the set is empty
|
|
remove()
|
Remove an element from a set. It the element
is not a member, raise a KeyError
|
|
symmetric_difference()
|
Return the symmetric difference of two sets
as a new set
|
|
symmetric_difference_update()
|
Update a set with the symmetric difference
of itself and another
|
|
union()
|
Return the union of sets in a new set
|
|
update()
|
Update a set with the union of itself and
others
|
A={1,2,3,4,5}
print(A)
print(len(A))
{1, 2, 3, 4, 5}
5
A.add(6)
print(A)
{1, 2, 3, 4, 5, 6}
print(A.copy())
{1, 2, 3, 4, 5, 6}
A.discard(3)
print(A)
{1, 2, 4, 5, 6}
print(A.pop())
1
print(A)
{2, 4, 5, 6}
A.remove(2)
print(A)
{4, 5, 6}
A.clear()
print(A)
print(len(A))
set( )
0
union
a={1,2,3,4,5}
b={4,5,6,7,8}
print(a|b)
print(a.union(b))
print(b|a)
print(b.union(a))
{1, 2, 3, 4, 5, 6, 7, 8}
{1, 2, 3, 4, 5, 6, 7, 8}
{1, 2, 3, 4, 5, 6, 7, 8}
{1, 2, 3, 4, 5, 6, 7, 8}
intersection
a={1,2,3,4,5}
b={4,5,6,7,8}
print(a&b)
print(a.intersection(b))
print(b&a)
print(b.intersection(a))
{4, 5}
{4, 5}
{4, 5}
{4, 5}
difference
a={1,2,3,4,5}
b={4,5,6,7,8}
print(a-b)
print(a.difference(b))
print(b-a)
print(b.difference(a))
{1, 2, 3}
{1, 2, 3}
{8, 6, 7}
{8, 6, 7}
symmetric difference
a={1,2,3,4,5}
b={4,5,6,7,8}
print(a^b)
print(a.symmetric_difference(b))
print(b^a)
print(b.symmetric_difference(a))
{1, 2, 3, 6, 7, 8}
{1, 2, 3, 6, 7, 8}
{1, 2, 3, 6, 7, 8}
{1, 2, 3, 6, 7, 8}
Note:
set support comprehension concept
s = { x for x in range(10) }
print(s)
{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
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