#PYTHON(DAY9)Sets and it's methods

 

#PYTHON(DAY9)

Sets and it’s methods

sets

• sets are a cluster of data values, they are not ordered
• we declare sets by using ‘{ }’
• sets do not have duplicate values
• we can use set class to perform task
• sets have methods that are unique to sets, like union, intersection etc
• to create an empty set, use set(). using {} gives an empty dictionary

x = {1,2,3,4, print, 'three'}
print(x, len(x), type(x), sep ='\n')

And the expected output is:

{1, 2, 3, 4, <built-in function print>, 'three'}
6
<class 'set'>

creating set with one element:

x = {8}
print(x)

And the expected output is:

{8}

Note: As, in tuples there is no need to place “ , “, for creating set with one element

Sets can not have duplicate elements

a = 'malayalam'
x = set(a)
print(x, len(x), type(x), sep = '\n')

And the expetced output is:

{'l', 'm', 'a', 'y'}
4
<class 'set'>

sets have no order in python

x = set()
print(x)

And the expected output is:

set()

Methods in set

Python has a set of built-in methods that you can use on sets

print(dir(set))

And the list methods are:

['__and__', '__class__', '__class_getitem__', '__contains__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__iand__', '__init__', '__init_subclass__', '__ior__', '__isub__', '__iter__', '__ixor__', '__le__', '__len__', '__lt__', '__ne__', '__new__', '__or__', '__rand__', '__reduce__', '__reduce_ex__', '__repr__', '__ror__', '__rsub__', '__rxor__', '__setattr__', '__sizeof__', '__str__', '__sub__', '__subclasshook__', '__xor__', 'add', 'clear', 'copy', 'difference', 'difference_update', 'discard', 'intersection', 'intersection_update', 'isdisjoint', 'issubset', 'issuperset', 'pop', 'remove', 'symmetric_difference', 'symmetric_difference_update', 'union', 'update']

Now, let’s talk about some of the important methods in set

add()

• it adds exactly one element to the set

x = {1,2,3,4}
x.add(6)
print(x)

output is:
{1, 2, 3, 4, 6}

x.add(5)
print(x)

output is:
{1, 2, 3, 4, 5, 6}

add() takes exactly one element only

pop()

• it is going to pop a random element, pop in sets takes no input/arg

print(x)
a = x.pop()
print(x,a, sep ='\n')

output is:
{1, 2, 3, 5}
{2, 3, 5}
1

copy()

a = set('hellow world!')
b = a
print(a,b, sep = '\n')
print()
a.update(['xx','yy'])
print(a,b, sep = '\n')
print()

output is:
{'!', 'h', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}
{'!', 'h', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}

{'!', 'h', 'yy', 'xx', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}
{'!', 'h', 'yy', 'xx', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}

a = set('hellow world!')
b = a.copy()
print(a,b, sep = '\n')
print()
a.update(['xx','yy'])
print(a,b, sep = '\n')
print()

output is:
{'!', 'h', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}
{'!', 'h', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}

{'!', 'h', 'yy', 'xx', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}
{'!', 'h', 'o', 'w', ' ', 'd', 'l', 'e', 'r'}

clear()

• clear() is used to clear the set

print(b)
b.clear()
print(b)

output is:
set()
set()