*Python Notes Unit 1, Part 3*

__UNIT – 1 (part 3)__

Introduction to Python Part 1

Introduction to Python

History and its Features

Basic Syntax

Understanding Python variables

Numeric data types

Using string data type and string operations

Basic Operators

Understanding coding blocks.

Defining list and list slicing,

Other Data Types- Tuples. List, Python Dictionary, Arrays, Associative Arrays/Hashes

**ARRAY IN PYTHON** -

1. An
array is a collection of common type of data structures having elements with
same data type.

2. Array
is mainly used to store collections of data.

3. Arrays
are handled by the “array” module. If you can create array using array module, elements
of the array must be of the same numeric type.

4. The
Arrays are especially useful when you have to processed the data dynamically.

5. Python
arrays are used when you need to use many variables which are of the same type.

* *

*Syntax
for create an Array in Python – *

** **You can declare an array in Python
while initializing it using the following syntax.

**arrayName = array.array(data Type, [array
items])**

**In
python, there are following operation can be performed on array – **

** **

**BASIC
ARRAY OPERATIONS
**

**(a)
****Adding/changing**

**(b)
****Removing/deleting**

**(c)
****Searching**

**(d)
****Slicing**

**(e)
****Looping**

**
**

** **

**Associative Array – **

1. Associate
array are also called maps or symbol tables or dictionaries.

2. In
an associative array, the values of the array are key-value pairs.

3. The
key represents a lookup value or an index. The value is the value stored for
that key.

4. Each
key must be unique.

5. The
Associative Array** **data structure is
an abstract data structure.

6. There
are several ways to implementing it, with the hash table being the most common.

**Hash Table – **

1.
A hash table has two
parts: An array and a hash function.

2.
The hash function is a
function that returns an integer given a key.

3.
The hash function is used
to determine where the value should be stored.

4.
The name of the key is
used to access its associated value.

5.
This makes searching for
values in a hash table very fast, irrespective of the number of items in the
hash table.

The hash table
data structure stores elements in key-value pairs where

(a)
**Key
– **unique integer that is used for indexing
the values

(b)
**Value
– **data that are associated with keys.** **

**Basic operators in Python **

**Operator – **

Operator
is a symbols which tells the interpreter to do a specific operation such as
arithmetic, comparison, logical and so on.

**In Python, there are
following types of Operators- **

**1.
****Arithmetic
Operator**

**2.
****Relational
Operator**

**3.
****Bitwise
Operator**

**4.
****Assignment
Operator**

**5.
****Logical
Operator **

** **

**Arithmetic Operator –
**

**An Arithmetic operator**
takes two operands as input, for perform a calculation and returns the result.

**For Example- **

** a= 2+3 **

**Here 2 and 3 are the
operands and + is the Arithmetic operator.**

**The result of the operation
is stored in the variable a.**

** **

**Relational Operator- **

**A Relational Operator **is used to
comparing two operands to decide a relation between them. Its returns a Boolean
value based on the condition.** **

**For Example-**

** 8>3 return true.**

**Here 8 and 3 are operands
and > is operator.**

**Bitwise Operator- **

**A bitwise operator**
performs operation on the operand bit by bit. **There are mainly 4 types of bitwise operator is used –**

**1.
****Bitwise
AND (&)**

**2.
****Bitwise
OR (|)**

**3.
****Bitwise
XOR (^)**

4. **Bitwise NOT (~)**

**Consider a = 2 **(10**) _{2} and b = 3 **(11

**)**

_{2}Perform
bitwise AND operation** **on the
operands-

a **&** b = 2 (10&11 = 10)_{2}

Perform
bitwise OR operation –

a **|** b = 3 (10|11 = 11)_{2}

Perform
bitwise XOR operation-

a **^** b = 1 (10^11=01)_{2}

Perform
bitwise NOT operation

**~**a = -3 ((00000010) = (11111101))_{2}

**Assignment Operator – **

**An Assignment operator**
is used to assign a value to a variable.

This
is usually combined with other operators where the operation is performed on
the operands and the result is assigned to the left side operands.

**For Example- **

**
a = 9 **

**Here “=” is an assignment operator, and the result is
stored in variable a.**

** **

**Logical Operator- **

**A logical operator** is used to make a
decision based on one or more conditions. The logical operators used in Python
are -

**1.
****and**

**2.
****or**

**3.
****not**

**For example – **

** a and b**

** a or b**

** not a**

** **

** **

*************************** THE END ***************************

Introduction to Python Part 1

Unit 2 Notes will uploaded ASAP keep studying.

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