Python has four types of data structure.
1. LIST
2. TUPLE
3. SET
4. DICTIONARY
List: The list is the data structure of item which are ordered, mutable and these are comma the separated value stored in square bracket.
The basic operation of List and functions:
1. Accessing elements
–[0],[1],[2],[3],[4].
2. Modifying individuals item- You can
modify in the list individually
users[0], users[-2].
3. Adding elements- You can add elements
in the list by users. append.
4. Removing elements- you remove any
item by their position or value of the item. users.remove(‘list_iem_name’).
5. List length- len() functions return the number in list.
6. Sorting a list –You can sort list
increasing or decreasing order
Sorting permanently =>
users.sort(),users.sort(reversed=True)
Sorting temporary=>
print(sorted(usres)),print(sorted,reversed=True))
7. Slicing a list: You can slice a
portion of the list [:3],[1:3],[-3:]
8. Copying a list => copy_users=[:]
#some example of List
users=['val','bob','mia','ron','ned']
first_item=users[0]
print(first_item)
# sorting a list permanently
users.sort()
print(users)
users.sort(reverse=True)
print(users)
# for usrers in users:
# print(users)
# finding length of the list
num_users=len(users)
print(num_users)
# slicing a list
first_three=users[:3]
print(first_three)
midle_three=users[1:4]
print(midle_three)
last_three=users[-3:]
print(last_three)
# copying a list
copy_of_users=users[:]
print(users)
Tupple: Tuple is a set of an item which
is ordered and immutable ().
Due to immutable in nature, we can’t apply so many functions like a list.
only count and index functions are there.
Set: Set is data structured which is ordered,
mutable in nature, and does not hold the duplicate value in the set.
Operations and functions of Set:
(A)
Creating
a set :{}
1. Duplicate element-does not hold the duplicate element in set.
2. Mutable -but may not contain mutable
items like a set, or even a dictionary.
3. Python set function
(B).Accessing a set in python: Since the set is not support
indexing so we can access the entire set at once. Because set does not support
slicing so we can’t access the element one by one or [:3].
(C).Deleting a set: Because the set is not indexed then we can’t
delete any element from the set. By using some method we can remove or discard
any item from the set.
Set.
Pop() ->It will pop an element from beginning one by one
Set. Clear() -> It will clear all
the element from set.
(D).
updating a set: You can add and update the number in your set.
(E)
Function on sets:
Len()->The len function return the
length of the functions.
Max() ->This function can return
the highest value from set.
Min()->This function can return the
Lowest value from the set.
Sum()->This function sum all the
value from the set.
All/any()->True or False
Sorted()->It
will sort the item in ascending order.
(E).Methods on set:
Union(),Intersection(),difference(),symmetric_difference,intersection_update,difference_updat
Symmetric_difference_update()
,copy,isdisjoint,issubset,issuperset,
(F).Operation on sets:
Membership: We can apply the ‘in’ and ‘not’ in python
operator on items for set. This tells us weather they are belong to set.
(H): Iterating on set: We can iterate on set in a for a loop.
(I): The
frozenset: A frozenset is in-effect an immutable set. You can’t change its
value. Also, a set can’t be used a key for a dictionary , but a frozenset can
d=set()
print(type(d))
#
=========Deleting===========
# we can't delete any item from the list but by suing discard or delete method we can
set={1,3,3,4,5,5,7}
set.discard(3)
print(set)
set.remove(5)
print(set)
# pop()
set.pop()
print(set)
# clear
set.clear()
print(set)
# Updating a set
numbers={1,1,2,2,3,3,4,5}
# numbers[9]
# print(numbers)
numbers.add(3.5)
print(numbers)
numbers.update([7,8],[1,10,9])
print(numbers)
# Functions on set
print(len(numbers))
print(max((numbers)))
print(min(numbers))
print(sum(numbers))
print(any(numbers))
print(all(numbers))
print(sorted(numbers))
# Methods on set
set1,set2,set3={1,2,3,4},{4,5,6},{4,5,7,8,9}
print(set1.union(set2,set3))
print(set2.intersection(set3))
print(set1.difference(set2))
print(set1.symmetric_difference(set2))
print(set1.intersection_update(set2))
print(set1.difference_update(set2))
print(set1.symmetric_difference_update(set2))
print(set3.copy)
print(set1.isdisjoint(set3))
print(set1.issubset(set2))
print(set1.issuperset(set1))
# Operation on set
# 'p' in {'a','c','p','d'}
for i in {'a','c','p','d'}:
print(i)
Dictionary: A dictionary has to contain
key-value with semicolon pair in the curly bracket.
Creating a dictionary: dict =
{‘a’:1,’b’:2,’c’:3}
(A): Python dictionary
with comprehension: It’s just like range function.
mydict={x*x:x
for x in range(8)}
print(mydict)
output= {0: 0, 1: 1, 4:
2, 9: 3, 16: 4, 25: 5, 36: 6, 49: 7}
(B): Dictionary with
mixed keys: The key-Val pair should not sa me necessary in dictionary.
dict3={1:'carrots','two':[1,2,3]}
(C)dict(): Using dict function we can
convert in dictionary.
dict(([1,2],[2,4],[3,6]))
(D): Declaring one key
more than once: Like set dictionary can’t hold more than one key.
mydict2={1:2,1:3,1:4,2:4}
(E):Declaring empty
dictionary and adding elements later: When you can add key-value pair in
dictionary.
animals={}
animals[1]='dog'
animals[2]='cat'
(F)Accessing python dictionary:
(a)accessing an entire python dictionary: print the dict name
(b)accessing a value: To access an item from a dictionary we can use
square bracket in the dictionary.
(c)get(): The Python dictionary get() functions takes a key as an
argument and returns the corresponding value.
Mydict.get(49)
Output=7
(G): Updating the value
of an Existing key: you can update the dictionary value by using square
bracket.
(H)You can delete the
item from dict like- del dict[2]
(I) In-built functions on
dictionary:
Len(),any()->return
true if any key has Boolean value.
All(),sorted()
->function returns a sorted sequence
key in ascending order dictionary.
(J)In-built methods of
dictionary:
Keys()-> used for
return the key of dictionary
Values()-> used for
return the value of dictionary
Items()->return the
key-value of dictionary
Get()->dict4.get(3,0
) it will return the key if there is in dictionary or return 0.
Clear()->represent the empty
dictionary
Copy()->copy
methods creates the shallow copy of the python dictionary.
Pop()->This method is used
to remove and display an item from the dictionary. It takes one to two
arguments. The first is the key to be deleted, while the second is the value
that’s returned if the key isn’t found.
Popitem(): pop item() method is
such that for a particular dictionary, it always pops pairs in the same order.
From keys()->This method
creates a new Python dictionary from an existing one.
Update():This method is used
for updating the dictionary as a key value.
Python Dictionary Operation:
Membership: We
can apply the ‘in’ and ‘not in’ operators on a Python dictionary to check
whether it contains a certain key.
Python Iterate dictionary: When
in a for loop, you can also iterate on a Python dictionary like on a list,
tuple, or set.
Nested Dictionary: Finally, let’s look at nested dictionaries. You can also place a
Python dictionary as a value within a dictionary. , dict1={4:{1:2,2:4},8:16}
# dictionary
-contain key-value pair
dict={x*x:x
for
x in range (8)}
print(dict)
#
updating the value of the existing key
dict1={1:2,3:4,5:6,7:8}
dict1[3]=9 #You can update the value
by assigning key in square bracket
print(dict1)
#
Deleting a dict
del
dict1[3]
print(dict1)
Difference between List, Tuple, Set
& Dictionary
List
|
Tupple
|
Set
|
Dictionary
|
List is
a collection that is ordered, mutable.
|
Tupple is
a collection that is ordered, immutable.
|
Collection of Unordered
and Unindexed items & mutable in nature.
|
A dictionary is a the collection which is unordered, changeable and indexed & Key: Value Pair
in Python.
|
Allows duplicate members[]
|
Tuples are faster than
lists as they are immutable& hold the duplicacy().
|
Does not take duplicate
Values{}.
|
Does not take duplicate
Values{}.
|
Lists are like arrays
declared in other languages.
|
|
Sets are not faster than
lists however they have an upper hand when it comes to membership testing.
|
|
Functios:append,remove,len
Sort,slicing,copy,pop
|
Functions: not support like list due to immutable in nature.
|
Functions:len,max,min,sum,all,
Any, sort, pop clear, delete
|
Functions:len ,all
Sorted,keys,values,items,get,
Clear, copy
|
