PYTHON - SETS |
Mathematically
a set is a collection of items not in any particular order. A Python set is
similar to this mathematical definition with below additional conditions.
- The elements
in the set cannot be duplicates.
- The elements
in the set are immutable ( cannot be modified) but the set as a whole is mutable.
- There is no
index attached to any element in a python set. So they do not support any
indexing or slicing operation.
Set Operations
The
sets in python are typically used for mathematical operations like union,
intersection, difference and complement etc.
We can
create a set, access it’s elements and carry out these mathematical operations
as shown below.
Creating a set
A set
is created by using the set function or placing all the
elements within a pair of curly braces.
Days
= set([“Mon”, “Tue”, “Wed”, “Thu”, “Fri”, “Sat”, “Sun”])
Months
= {“Jan”, “Feb”, “Mar”}
Dates
= {15, 18, 12}
print
(Days)
print
(Months)
print
(Dates)
|
When
the above code is executed, it produces the following result. Please note how
the order of the elements has changed in the result.
set(['Wed',
'Sun', 'Fri', 'Tue', 'Mon', 'Thu', 'Sat'])
set(['Jan',
'Mar', 'Feb'])
set([12,
18, 15])
|
Accessing
Values in a Set
We
cannot access individual values in a set. We can only access all the elements
together as shown above. But we can also get a list of individual elements by
looping through the set.
Days=set(["Mon","Tue","Wed","Thu","Fri","Sat","Sun"])
for d in Days:
print(d)
|
When
the above code is executed, it produces the following result.
Wed
Sun
Fri
Tue
Mon
Thu
Sat
|
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