Creating python sets
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# creating simple set
s = { “cat”, “dog”, “bird” }
print(s)
print(type(s))
# creating set by special function set()
s = set( [ “horse”, “cat”, “cow” ] )
print(s)
print(type(s))
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Standard operations with python sets
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# set of animals
set1 = { “cat”, “dog”, “bird” }
print(set1)
# second set of animals
set2 = { “cow” , “cat”, “horse”, “chicken” }
print(set2)
# make union (sum of two sets)
set3 = set1 | set2
print(set3)
# make difference between two sets
set3 = set1 – set2
print(set3)
# verify different order for difference of two sets
set3 = set2 – set1
print(set3)
# intersection = take these elements that are in both sets
set3 = set1 & set2
print(set3)
# symmetric difference = is the same as union with boths sets minus intersection
set3 = set1 ^ set2
print(set3)
set3 = (set1 | set2) – (set1 & set2)
print(set3)
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Available functions with python sets
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# simple set of numbers
set1 = { 10, 20, 30, 40, 50 }
set2 = { 60, 70, 80, 90 }
# set is like list without defined order of elements
print(set1)
print(type(set1))
# adding new element to set
set1.add(60)
print(set1)
# add again the same element, can you ?
set1.add(60)
print(set1)
# use function for intersection
set3 = set1.intersection(set2)
print(set3)
# use function for difference
set3 = set1.difference(set2)
print(set1)
print(set2)
print(set3)
# make union of two sets
set3 = set1.union(set2)
print(set3)
# remove element 60 from set
set1.discard(60)
print(set1)
# copy existing set
set3 = set1.copy()
# clean set1 set
set1.clear()
# verify that copy is still the same
print(set1)
print(set3)
# remove element from the set
set2.pop()
print(set2)
# remove specified element from set
set2.remove(60)
print(set2)
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Running sets with other data types in python
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# get difference between two lists using sets
list1 = [10,20,30,40]
list2 = [30,40,50,60]
# get the difference between two lists converted into sets
set1 = set(list1) – set(list2)
# convert set back to list
list1 = list(set1)
print(list1)
print(type(list1))
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