Python Topics
1.
List
2.
Tuples
3.
Strings
4.
Dictionaries
5.
Set
1.
Python List
Python List
--------------
·
Lists are used to store multiple items in
a single variable.
·
Python list (all items) created inside a
square bracket ([])
·
List are mutable (can alter List (add,
update, delete)
·
List items are Empty, ordered, changeable,
and allow duplicate values.
Python List Syntax:
-----------------------
list_name = [value1, value2, value3,...,
value-n]
Example:
----------
->Empty List:
list=[ ]
->Integer List:
list=[1,2,3]
->Floating List:
list=[1.5,2.5,3.6]
->string List:
list=["hello",
"welcome", "python"]
->Mixed List:
list=[1,2.5,"hello"]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Accessing Lists
------------------
àList
items are indexed, the first item has index [0], the second item has
index [1] etc.
-Forward
Index: 0, 1, 2, 3, 4...
-Backward Index: -1,-2,-3,-4...
Ex:
str=[10,20,30,40,50,60]
str[0]=10=str[-6],
str[1]=20=str[-5],
str[2]=30=str[-4],
str[3]=40=str[-3],
str[4]=50=str[-2],
str[5]=60=str[-1].
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 1: Example
Program for Display & Accessing Python List
a
= [ ]
b
= [10,20,3,5,8,1]
c
= [10.5,20.5,3.5]
d
= ["welcome", "python"]
e
= [12, 5.6, "hello", 25]
print(a)
print(b)
print(c)
print(d)
print(e)
list1
= [10,20,30,40,50,60]
print(list1)
print
(list1 [0])
print
(list1 [-1])
print
(list1 [1:3])
print
(list1 [1:])
print
(list1 [:3])
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Python List Methods
---------------------------
1.
append()- Adds an element at the end of the list
2.
clear() - Removes all the elements from the list
3.
copy() - Returns a copy of the list
4.
count() - Returns the number of elements with the specified value
5.
extend()- Add the elements of a list (or any iterable), to the end of the
current list
6.
index() - Returns the index of the first element with the specified value
7.
insert()- Adds an element at the specified position
8.
pop() - Removes the element at the
specified position
9.
remove()- Removes the first item with the specified value
10.reverse()-Reverses
the order of the list
11.sort() - Sorts the list
12.min(list):
Returns the minimum value from the list given.
13.max(list):
Returns the largest value from the given list.
14.len(list):
Returns number of elements in a list.
15.cmp(list1,list2):
Compares the two list.(Not Working 3)
16.list(sequence):
Takes sequence types and converts them to lists.
17.del
: delete a list
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 2: Example
Program for Python Methods
a
= [20,30,10,15,10,25]
a1
= ["red", "green", "blue"]
print
("List are", a)
print
("List are", a1)
a.append(5)
print("Append
: ",a)
b=a.copy()
print("Copy
:",b)
b.clear()
print("clear
:",b)
print("10
no of times :",a.count(10))
print("Index
:",a1.index("green"))
a1.insert(1,"orange")
print("Insert
:",a1)
a1.pop(1)
print("Now
List :",a1)
a1.remove("green")
print("Now
List :",a1)
a1.reverse()
print("Reverse
List :",a1)
a1.sort()
print("Sorting
List :",a1)
print("Max
:",max(a1))
print("Min
:",min(a1))
print("Len
:",len(a1))
a1=["one","two","three"]
a2=["red","green","blue"]
a1.extend(a2)
del
a1
#print(a1)
Error
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2.
Python Tuple
Python Tuple
-----------------
§ Tuple is a sequence of immutable objects
§ Tuple can’t be changed; you cannot change elements of a tuple once it is
assigned.
§ Tuple
objects are enclosed within parenthesis and separated by comma.
§ Tuple
can be empty, Tuple there is no order
§ Tuple
values are Repeated (Duplicate)
Syntax for Tuples:
--------------------
tuple_name = tuple ( (value1, value2, value3,..., valuen) )
Example:
-----------
->Empty Tuple:
tuple1=tuple ()
->Integer Tuple:
tuple1=tuple ((1,2,3))
->Floating Tuple:
tuple1=tuple ((1.5,2.5,3.6))
->string Tuple:
tuple1=tuple (("hello", "welcome",
"python"))
->Mixed Tuple:
tuple1=tuple((1,2.5,"hello"))
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Accessing Tuple
------------------
àTuple
items are indexed, the first item has index [0], the second item has
index [1] etc.
-Forward
Index: 0, 1, 2, 3, 4...
-Backward Index: -1,-2,-3,-4...
Ex:
str=tuple ((10,20,30,40,50,60))
str[0]=10=str[-6],
str[1]=20=str[-5],
str[2]=30=str[-4],
str[3]=40=str[-3],
str[4]=50=str[-2],
str[5]=60=str[-1].
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 1: Example
Program for Display & Accessing Python Tuple
a=tuple
()
b=tuple
((10,20,3,5,8,1))
c=tuple
((10.5,20.5,3.5))
d=tuple
(("welcome", "python"))
e=tuple
((12, 5.6, "hello", 25))
print(a)
print(b)
print(c)
print(d)
print(e)
a=tuple
((10, 3, 5, 20, 7, 20))
print
(a)
print
(a[0])
print
(a[-1])
print
(a[1:3])
print
(a[2:])
print
(a[:2])
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Python Tuple Methods
------------------------------
1.count()
- Returns the number of elements with the specified value
2.index()
- Returns the index of the first element with the specified value
3.min(tuple):
Returns the minimum value from the tuple given.
4.max(tuple):
Returns the largest value from the given tuple.
5.len(tuple):
Returns number of elements in a tuple.
6.Tuple(sequence): Takes sequence types and converts them to Tuples.
7.del
: delete a Tuple
8.sum
: sum of a tuples
9.sorted
: sorted of a tuples
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 2: Example
Program for Python Tuples Methods
a=tuple
((20,30,10,15,10,25))
print(a)
print("10
count :",a.count(10))
print("Index
:",a.index(10))
print("Max
:",max(a))
print("Min
:",min(a))
print("Len
:",len(a))
print("Sum
:",sum(a))
print("Sorted
:",sorted(a))
del
a
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3.
Python Strings
Python
Strings:
--------------------
-String is a collection characters or sequence of character
-String is noted by single quotes (‘ ‘) or double quotes (“ ”)
-string is immutable (can’t alter strings)
-string character stored on sequential order
Syntax:
Variable = "strings"
(or) Variable = ‘strings‘
Ex:
str1="welcome"
str2='welcome'
Accessing strings
----------------------
-string character can be access both Forward and backward format
-Forward Index: 0,1,2,3,4...
-Backward Index: -1,-2,-3,-4...
Ex:
str="PYTHON"
str[0]='P'=str[-6],
str[1]='Y'=str[-5],
str[2]='T'=str[-4],
str[3]='H'=str[-3],
str[4]='O'=str[-2],
str[5]='N'=str[-1].
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 1: Example
Program Python strings slice notations
str1="welcome to python"
print(str1)
print(str1[0])
print(str1[1])
print(str1[1:])
print(str1[:2])
print(str1[0:2])
str1="hello"
print(str1[::-1]) #olleh
~~~~~~~~~~~~~~~~~~~~~~~~~~~
String Operator:
-------------------
1. Basic
Operator
a.
String Concatenation Operator (+)
b.
Replication Operator (*)
2. Membership Operator
a.
in
b.
not in
3. Relational Operator
<,><=,>=,==,!=
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 2: String Operators
#using string concatenation operator
str1="welcome"
str2="to python"
str3=str1+" "+str2
print(str3)
str1="welcome"
str2=20
#str3=str1+str2 #Error
str3=str1+str(str2)
print(str3)
#using string Replication operator
str1="welcome\n"*5
print(str1)
#using string Membership operator
str1="welcome to python"
print("welcome" in str1)
print("chennai" in str1)
print("chennai" not in str1)
print("welcome" not in str1)
#using string Relational operator
# <,><=,>=,==,!=
str1="jahab"
str2="jahab"
str3="trichy"
print(str1==str2) #true
print(str1==str3) #false
print(str1!=str2) #false
str1="A" #65
str2="a" #97
print(str1!=str2) #true
print(str1==str2) #false
print(str1<str2) #true
print(str1>str2) #false
str1="a"
str2="a"
print(str1>str2) #false
print(str1>=str2) #true
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
------------------
1. capitalize()
2. count(string,begin,end)
3. endswith(suffix ,begin=0,end=n)
4. find(substring ,beginIndex, endIndex)
5. index(subsring, beginIndex, endIndex)
6. isalnum()
7. isalpha()
8. isdigit()
9. islower()
10.isupper()
11.isspace()
12.len(string)
13.lower()
14.upper()
15.startswith(str ,begin=0,end=n)
16.swapcase()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 3: using string methods
str1="welcome to msg"
print(str1)
print(str1.capitalize())
str2="msg"
print(str1.count(str2))
print(len(str1))
print(str1.startswith("welcome"))
#true
print(str1.startswith("welcometttt"))
#false
print(str1.endswith("msg")) #true
print(str1.endswith("msg100"))
#false
print(str1.find("msg"))
print(str1.find("msg1")) #-1
print(str1.index('m'))
str1="python3.1"
str2="python"
print(str1.isalpha()) #false
print(str2.isalpha()) #true
print(str2.isalnum()) #true
print(str1.isalnum()) #false
str1="100"
print(str1.isdigit()) #true
str1="100a"
print(str1.isdigit()) #false
str1="welcome"
str2="WElcome"
str3="WELCOME"
print(str1.islower()) #true
print(str2.islower()) #false
print(str3.isupper()) #true
print(str3.isspace()) #false
str1="welcome"
str2="WELCOME"
print(str1.upper())
print(str1.lower())
print("swap case")
str1="WElcoMe"
print(str1.swapcase())
print("Left and right Trim")
str1="
welcome"
str2="welcome "
print(str1)
print(str1.lstrip())
print(str1.rstrip())
str1="welcome to python"
print(str1.replace("to","too"))
print(str1)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4.
Python Dictionary
Python Dictionary
-------------------------
·
Dictionaries
are used to store data values in key: value pairs.
·
Dictionaries
can be referred to by using the key name. [key name not duplicate]
·
A
dictionary is a collection which is ordered, changeable.
Syntax for Dictionary:
---------------------------
dic_name = {Key1:Data1, Key2:Data2….}
Example:
->Empty Dictionary:
dic1={}
->Integer Value
Dictionary:
dic1={100:10,101:5,102:20}
->Floating Value
Dictionary:
dic1={100:10.5,101:5.6,102:20.6}
->string Value
Dictionary:
dic1={1:"hello",2:"welcome",3:"python"}
dic2={'Name':'jahab','Qualification:M.sc.Mphil','class':1}
->Mixed Value
Dictionary:
dic1={1:1,2:2.5,3:"hello"}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 1: Example
Program for Python Dictionary
dic1={}
print(dic1)
dic1={100:10,101:5,102:10,104:1,103:30,103:20}
print(dic1)
dic1={100:10.5,101:5.6,102:20.6}
print(dic1)
dic1={1:"hello",2:"welcome",3:"python"}
print(dic1)
dic1={1:1,2:2.5,3:"hello"}
print(dic1)
#accessing
dictionaries data
a1={100:10,101:20,102:30}
a2={'Name':'jahab','Qualification':'M.sc.Mphil','class':1}
a3={1:1000,"Name":"Jahab","Age":30}
print(a1[100])
print(a2['Name'])
print(a3['Age'])
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
------------------------------
Python Dictionary Methods
------------------------------
1. update() - Updates the dictionary with the specified key-value pairs
2. min(dic):
Returns the minimum value from the tuple given.
3. max(dic):
Returns the largest value from the given dictionary.
4. len(dic):
Returns number of elements in a dictionary.
5. clear()
: Clear dictionary
6. sum
: sum of a Dictionary Values
7.sorted
: sorted of a dictionary values
8. pop() Removes the element with the specified key
9. popitem() Removes the last inserted key-value pair
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 2: Example
Program for Dictionary Methods
dic1={1:1000,2:1001,7:30,5:2000}
print(dic1)
dic1.update({8:1000})
print(dic1)
print ("Minimum:",min(dic1))
print ("Maximum:",max(dic1))
print ("Length :",len(dic1))
print ("sum :",sum(dic1))
print ("sorting :",sorted(dic1))
print ("Get item :",dic1.get(5))
print(dic1.pop(2))
print(dic1)
print(dic1.popitem())
print(dic1)
dic1.clear()
print(dic1)
del dic1
print(dic1)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5.
Python sets
Python Set
--------------
§ Sets
are used to store multiple items in a single variable. (duplicates not allowed)
§ set is a collection which is unordered, unindexed
and unchangeable but you can remove items and
add new items.
§ Sets
are written with curly brackets.
Syntax for set:
-----------------
set_name = set ()
Example:
->Empty Set:
a1=set ()
->Integer Set:
a1=set ((1,2,3))
->Floating Set:
a1=set ((1.5,2.5,3.6))
->string Set:
a1=set (("hello", "welcome",
"python"))
->Mixed set:
a1=set ((1,2.5,"hello"))
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 1: Example
program for set
a=set
()
print(a)
a1=set
((1,2,3))
print(a1)
a2=set
((1.5,2.5,3.6))
print(a2)
a3=set
(("hello", "welcome", "python"))
print(a3)
a4=set((1,2.5,"hello"))
print(a4)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--------------------------------------------
Python set Methods
-------------------------------
1.
remove()-Removes Element from the Set
2.
add() -adds element to a set
3.
copy() -Returns Shallow Copy of a Set
4.
clear() -remove all elements from a set
5.
difference()-Returns Difference of Two Sets
6.
discard()-Removes an Element from The Set
7.
intersection()-Returns Intersection of Two or More Sets
8.
pop() -Removes an Arbitrary Element
9.
union() -Returns Union of Sets
10.update()-Add
Elements to The Set.
11.len() -Returns Length of an Object
12.max() -returns largest element
13.min() -returns smallest element
14.set() -returns a Python set
15.sorted()-returns
sorted list from a given iterable
16.sum() -Add
items of an Iterable
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 2: using Python
Set Methods
a=set([10,20,45,5,9,2,78,2])
print
(a)
a.add(50)
print
(a)
a.update([12])
print
(a)
a.discard(12)
print
(a)
a.remove(2)
print
(a)
print ("Minimum:",min(a))
print ("Maximum:",max(a))
print ("Length :",len(a))
print ("sum :",sum(a))
print ("sorting :",sorted(a))
print
(a)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Program 3: Example
Program for set Operations
A
= set([1, 2, 3, 4, 5])
B
= set([4, 5, 6, 7, 8])
print
(A)
print
(B)
print
(A|B)
print
(A.union(B))
print
(A&B)
print
(A.intersection(B))
print
(A-B)
print
(A.difference(B))
myset=set("apple")
print
('a' in myset)
print
('c' in myset)
print
('c' not in myset)
print
('a' not in myset)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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