Python Notes for B-Tech , Bsc , Bca....
What is Python?
* Python is a high level , general purpose object oriented programming language.
* It was created by Guido Van Rossum in 1991 at CWI in Netherland.
Syntex-
print("Hello")
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Features of Python:-
* Simple and easy to learn
* Open source
* Platform independent
* Rich Library
* Portable
* Interpreted
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Applications of Python :-
* Web development
* Game development
* IOT development
* AI
* Machine Learning
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# Input / Output :-
* For taking input in python , we have input()
* For taking output in python , we have print()
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Python Comments :- Comments are nothing but ignorable part of python program that are ignored by the interpreter.
There are 2 types of Comments -
1. Single line comment
syntex- #..........
2. Multi line comment
syntex- ''' ..........
..........
........
'''
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Keywords:- Keywords are the words whose meaning is already being defined in Python interpreter.
* Python keywords are Case sensitive.
* We cant use a keywords as a variable name, method name or any other identifiers.
* Total 33 keywords in Python.
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Data Type:- Data Type represent the different kinds of values that we stored on the variable.
* Basic data type in python:-
1. Number
2. String
3. dict
4. set
5. List
6. tuple
* We do not need to specify the data type explicitly , based on value types allocated automatically.
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Variable :- Variable is the name of memory location where we can store different type of values.
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Python Interpreter:- A python interpreter is a computer program that convert each high-level program statement into machine code.
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Python Shell:- The python shell is the interpreter that executes your Python program , other piece of Python code or simple commands.
It is also used to execute a single Python commands and display the result.
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Python Identation:- It refers to adding white space before a statement to a particular block of code. In another words a, all the statement with the same space to the right , belong to the same code block.
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Literals:- Literals are constant values assigned to constant variable. It represent fixed values that cannot be modified.
* We mainly have five types of literals which includes string literals, numeric literals, boolean literals, literal collections and a special literal None.
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Python Operators:- They are used to perform operations on values and variable.
Types :-
1) Arithmetic Operator- They are used to perform operations on values and variables.
example : + , - , * , /
2) Logical Operator- They perform LogicalAnd , LogicalOr and LogicalNot operations. They are used to combine conditional statement.
example : OR , NOT , AND.
3) Bitwise Operator- They act on bits and perform the bit-by-bit operations. They are used to operate on binary number.
example: & , >> , << , | etc .
4) Assignment Operator- They are used to assign values.
example: = , += , -= , etc.
5) Relational Operator- They are used to compare the operand values.
example: == , > , < , etc
6) Ternary Operator- It allows us to evaluate if a condition is true or false.
example: if , else .
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UNIT-2
Flow Control:- Flow Control describe the order in which statement will be executed at runtime.
1. Conditional Statement-
👉 if statement -
syntex - if condition :
statement
👉 if else -
syntex- if condition:
statement
else:
statement
👉else if
syntex- if condition:
statement
elif condition:
statement
else:
statement
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Example of else if ::
age = int (input ("Enter your age: "))
if age<18 :
print('You are too young to marry')
elif age>60:
print('You are too old to marry')
else:
print("we will find a perfect match for you")
output ~
Enter your age: 25
We will find a perfect match for you
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2. Iterative statement-
👉 for loop
syntex- for var-name in range(start,end):
statement
Example of for loop:-
table = int(input("Enter a number : "))
for number in range(1,11):
print(table * number)
output~
Enter a number : 6
6 12 18 24 30 36 42 48 54 60
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👉 while loop
syntex- while condition:
statement
Example of while loop-
password = "vaibhav"
input_password = input ("enter password :")
while password != input_password:
input_password = input("enter password :")
else :
print("unloacked !! ")
output~
Enter password :vaibhav
unlocked !!
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3. Loop control statement -
👉Continue statement
example-
for num in range(1,11):
if num % 2 == 0 :
continue
else:
print(num)
output~
1 3 5 7 9
👉break statement
example -
for num in range(1,11) :
if num % 2 == 0:
break
else:
print(num)
output~
1
👉pass: The pass statement is used as a placeholder for future code. When the pass statement is executed , nothing happen but you avoid getting an error when empty code is not allowed.
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UNIT-3
List:- List is a data structure which is also called collection of items, in which we can store anything like-string, float , integer.
syntex- list-name=[item1 , item2, ......... , item n ]
Note- * We write the item of the list inside "square brackets" ([]) and each item is seperated by "commas" (,).
* Duplicate are allowed.
* Mutable in nature.
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Program to print using indexing :-
list1 = [10, 'vaibhav' , true , 10.5 , 'bhatnagar' , 10]
print(list1[2])
output~ [true]
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Program to print by slicing :-
list2 = [10 , 'vaibhav' , true , 10.5 , 10]
print( list2[1:4] )
output~ [ 'vaibhav' , true , 10.5]
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Count method () : Count () is a Python in-built function that returns the number of times an object appears in a list.
Example-
list2=[10 , 'vaibhav' , true , 10.5 , 10]
print(list2.count(10))
output: 2
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index method () : It return the position at the first occurence of the specified value.
Example- list2 = [10 , 'vab' 20 , 13.5 , 30 ]
print(list2.index(30))
output- 4
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insert method () : It insert the specified value at the specified position.
Example-
list3= [10 , 'vab' , 30 , 40.5]
list3.insert(3 , "Hello")
print(list3)
output- [10 , 'vab' , 30 , 'Hello' , 40.5]
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pop method () : It is used to delete the element from the specified position.
Example-
list4= [10 , 'vab' , 30]
list4.pop(2)
print(list4)
output- [10 , 'vab']
* IF WE DOES NOT GIVE INDEX POSITION THAN BY DEFAULT IT WILL DELETE LAST ELEMENT
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Python Tuple:- It is a data structure which is also called Collection of items , in which we can store anything like string , float , integers.
Syntex: tuple-name=(item 1 , item 2 , ..... item n)
Note- * We write the item of the tuple inside parathesis "()" and each item is seperated by comma ",".
* Duplicates are allowed.
* Immutable in Nature.
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Set:- Set is a data structure which is also called collection of items in which we can represent a group of unique value as a single entity.
Syntex: set-name={item 1 , item 2 , .......item n }
* We write the item of set inside the curly braces "{}" .
* Insertion order is not preserved.
* Indexing and slicing not safe.
* Hetrogenous element are allowed.
* Mutable in Nature.
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Dictionary:- Dictionary is a data structure in which we represent a group of object as key-value pair.
syntex: dict_name = {"key": "value"}
Note-
* Insertion order is preserved.
* Indexing and slicing not work.
* Hetrogenous element are allowed.
* Mutable in nature.
* Key must be unique , but duplicates value are allowed.
Create Empty Dict:-
var=dict()
print(type(var))
or
var = {}
print(type(var))
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