Python set()

 list_numbers = [1, 2, 3, 4, 2, 5] 
# create set from list numbers_set = set(list_numbers)
 print(numbers_set) # Output: {1, 2, 3, 4, 5}

set() Syntax

The syntax of set() is:

set(iterable)

Also Read: Python sets

set() Parameters

set() takes a single optional parameter:

• iterable (optional) - a sequence (string, tuple, etc.) or collection (set, dictionary, etc.) or an iterator object to be converted into a set.

set() Return Value

set() returns:

• an empty set if no parameters are passed
• a set constructed from the given iterable parameter

Example 1: Create sets from string, tuple, list, and range

 # empty set print(set()) # from string 
print(set('Python'))
 # from tuple print(set(('a', 'e', 'i', 'o', 'u'))) # from list print(set(['a', 'e', 'i', 'o', 'u'])) # from range 
print(set(range(5)))

Output

 set() {'P', 'o', 't', 'n', 'y', 'h'} {'a', 'o', 'e', 'u', 'i'} {'a', 'o', 'e', 'u', 'i'} {0, 1, 2, 3, 4}

Note: We cannot create empty sets using { } syntax as it creates an empty dictionary. To create an empty set, we use set().

Also Read: Python range()

Example 2: Create sets from another set, dictionary and frozen set

 # from set print(set({'a', 'e', 'i', 'o', 'u'})) # from dictionary 
print(set({'a':1, 'e': 2, 'i':3, 'o':4, 'u':5}))
 # from frozen set 
frozen_set = frozenset(('a', 'e', 'i', 'o', 'u')) print(set(frozen_set))

Output

 {'a', 'o', 'i', 'e', 'u'} {'a', 'o', 'i', 'e', 'u'} {'a', 'o', 'e', 'u', 'i'}

Example 3: Create set() for a custom iterable object

 class PrintNumber: def __init__(self, max): self.max = max def __iter__(self): self.num = 0 return self def __next__(self): if(self.num >= self.max): raise StopIteration self.num += 1 return self.num # print_num is an iterable print_num = PrintNumber(5) # creating a set 
print(set(print_num))

Output

 {1, 2, 3, 4, 5}