Sets in Python

Sets

     A set is unordred collection of items with no duplicate. It can be used to eliminating duplicates or membership testing. Set also supports union, intersection, difference and symmetric difference. Set can be initialized using set().
     Set can be initialized using set().
set1 = set()
Set has following methods

set.add(element)

     Add element to set. If element already present nothing happens.

set.clear()

     Remove all elements and clear the set.

set.copy()

     Returns shallow copy set.

set.difference(another_set[s])

     Returns the difference of two or more sets as new set.

set.difference_update(another_set)

     Remove all elements of another from this set.

set.discard(element)

     Remove an element from set if is a member.

set.intersection(another_set[s])

     Returns the intersection of two or more sets as new set.

set.intersection_update(another_set)

     Update a set with the intersection of itself and another.

set.isdisjoint(another_set)

     Return True if two sets have null intersection, means that Returns true if the set have elements otherwise False.

set.issubset(super_set)

     Check whether super set contains this set. It Returns True if super set has all elements of this set and False Otherwise.

set.issuperset(sub_set)

     Check whether this set contains another set. It Returns True if this set has all elements of the sub set and False Otherwise.

set.pop()

     Remove and return an arbitrary set element and Raises KeyError if set is empty.

set.remove(element)

     Remove an element from if it is member and If the element is not a member, raise KeyError.

set.symmetric_difference(another_set)

     Returns the symmetric difference of two sets as a new set. i.e. All elements that are in exactly in one of the sets.

set.symmetric_difference_update(another_set)

     Update a set with the symmetric difference of itself and another.

set.union(another_set)

     Returns the union of sets as a new set. i.e. All elements that are in either set.

set.update(another_set)

     Update a set with the union of itself and another set.
Let's understand this by example code
 
>>> x=set()
>>> x.add(3)
>>> x.add(7)
>>> x.add(9)
>>> x
set([3, 7, 9])
>>> l = [3, 5, 8, 9, 11, 19]
>>> y = set(l)
>>> y
set([3, 5, 8, 9, 11, 19])
>>> z=y.copy()
>>> z
set([19, 3, 5, 8, 9, 11])
>>> x.difference(y)
set([7])
>>> z.discard(5)
>>> z
set([19, 3, 8, 9, 11])
>>> y.intersection(x)
set([9, 3])
>>> x.isdisjoint(y)
False
>>> z.issubset(y)
True
>>> y.issuperset(x)
False
>>> z.pop()
19
>>> y.remove(8)
>>>  x.symmetric_difference(z)
set([8, 11, 7])
>>>  x.union(y)
set([3, 5, 7, 9, 11, 19])
>>> x
set([9, 3, 7])
>>> y
set([3, 5, 9, 11, 19])
>>> z.clear()
>>> z
set([])
>>> x&y
set([9, 3])
>>>  x|y
set([3, 5, 7, 9, 11, 19])
>>> y-x
set([19, 11, 5])
>>> y^x
set([19, 11, 5, 7])

Keep Following, For More.

Comments

Post a Comment

Popular posts from this blog

Getting Started With Python

     Python is an easy to learn, powerful, general purpose programming language. It has efficient high-level data structures and a simple but effective approach to object-oriented programming. Python’s elegant syntax and dynamic typing, together with its interpreted nature, make it an ideal language for scripting and rapid application development in many areas on most platforms.     The Python interpreter and the extensive standard library are freely available in source or binary form for all major platforms from the Python Web site, https://www.python.org/ and may be freely distributed. The same site also contains distributions of and pointers to many free third party Python modules, programs and tools, and additional documentation.     The Python interpreter is easily extended with new functions and data types implemented in C or C++ (or other languages callable from C). Python is also suitable as an extension ...
Read more

Python List

List      List is data structure in python more like array in c or java. But in python list is mutable.      List is initialized in python using list class or just []. list1 = [] list2 = list() Below are some methods of list object list.append(item)      Add an Item to end of the list. list.count(item)      Returns number of time item appears in the list. list.extend(anotherList)      Extend the list by appending all the items from the given list. list.index(item, [start], [end])      Returns the first index of value. If specified optional arguments start or end, the item is searched within start and end. Raises ValueError if item not present. list.insert(index, item)      Insert an item at a given position, the element is inserted before the index. list.pop([index])      Remove an item from the ...
Read more

The dir Function

dir()      The built-in dir() lists names from modules. It returns a sorted list of strings.      Let's import regular expression module:- >>> import re >>> dir(re) ['DEBUG', 'DOTALL', 'I', 'IGNORECASE', 'L', 'LOCALE', 'M', 'MULTILINE', 'S', 'Scanner', 'T', 'TEMPLATE', 'U', 'UNICODE', 'VERBOSE', 'X', '_MAXCACHE', '__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '__version__', '_alphanum', '_cache', '_cache_repl', '_compile', '_compile_repl', '_expand', '_pattern_type', '_pickle', '_subx', 'compile', 'copy_reg', 'error', 'escape', 'findall', 'finditer', 'match', 'purge', 'search', 'split', ...
Read more