sets in python code example

Example 1: switching keys and values in a dictionary in python [duplicate]

my_dict = {2:3, 5:6, 8:9}

new_dict = {}
for k, v in my_dict.items():
    new_dict[v] = k

Example 2: python set &

>>> A = {0, 2, 4, 6, 8};
>>> B = {1, 2, 3, 4, 5};

>>> print("Union :", A | B)  
Union : {0, 1, 2, 3, 4, 5, 6, 8}

>>> print("Intersection :", A & B)
Intersection : {2, 4}

>>> print("Difference :", A - B)
Difference : {0, 8, 6}

# elements not present both sets
>>> print("Symmetric difference :", A ^ B)   
Symmetric difference : {0, 1, 3, 5, 6, 8}

Example 3: python sets

# You can't create a set like this in Python
my_set = {} # ---- This is a Dictionary/Hashmap

# To create a empty set you have to use the built in method:
my_set = set() # Correct!


set_example = {1,3,2,5,3,6}
print(set_example)

# OUTPUT
# {1,3,2,5,6} ---- Sets do not contain duplicates and are unordered

Example 4: sets in python

The simplest way to create set is:
1. from list
code:
	s = [1,2,3]
	set = set(s)
	print(set)

2. s,add() method
code:
	set.add(1)
	set.add(2)
	set.remove(2)
	print(set)  // 1

3. Set conatins unique elements

Example 5: sets in python

basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}
print(basket)                      # show that duplicates have been removed
# OUTPUT {'orange', 'banana', 'pear', 'apple'}
print('orange' in basket)                 # fast membership testing
# OUTPUT True
print('crabgrass' in basket)
# OUTPUT False

# Demonstrate set operations on unique letters from two words

print(a = set('abracadabra'))
print(b = set('alacazam'))
print(a)                                  # unique letters in a
# OUTPUT {'a', 'r', 'b', 'c', 'd'}
print(a - b)                             # letters in a but not in b
# OUTPUT {'r', 'd', 'b'}
print(a | b)                              # letters in a or b or both
# OUTPUT {'a', 'c', 'r', 'd', 'b', 'm', 'z', 'l'}
print(a & b)                              # letters in both a and b
# OUTPUT {'a', 'c'}
print(a ^ b)                              # letters in a or b but not both
# OUTPUT {'r', 'd', 'b', 'm', 'z', 'l'}

Example 6: sets in python

set_of_base10_numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0}
set_of_base2_numbers = {1, 0}

intersection = set_of_base10_numbers.intersection(set_of_base2_numbers)
union = set_of_base10_numbers.union(set_of_base2_numbers)

'''
intersection: {0, 1}:
	if the number is contained in both sets it becomes part of the intersection
union: {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}:
	if the number exists in at lease one of the sets it becomes part of the union
'''